General

Required Navigation Performance (RNP) Approaches: Guidance for Flight Crews

ThomasYoung — Mon, 10 Nov 2025 18:26:30 +0000

Required Navigation Performance (RNP) Approaches: Guidance for Flight Crews

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General

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SKYbrary

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SKYbrary

Definition

This article provides general guidance on flying Required Navigation Performance (RNP) approaches in transport-category aircraft equipped with modern electronic flight instrument systems (EFIS), and a flight management system (FMS). The following information serves as broad methodology and does not supersede aircraft-specific guidance in the relevant standard operating procedures (SOP).

Philippines airlines A350 [ Source: wiki commons. Author: James.cgs, 15 Dec 24]

Description

The naming of approaches that use RNP technology is not yet standard across the world. In the United States, an RNP approach chart might be labeled, for example: RNAV (RNP) Z 13R. In Europe, the same approach might be labeled: RNP Z 13R. Regardless of naming convention, RNP implies a GPS-based approach that requires a certain level of accuracy from an aircraft's navigational systems. On-board monitoring alerts pilots if required performance is not met. This can happen due to system malfunction or a lapse in reception from an adequate number of GPS satellites. An alert that warns of an unreliable GPS signal is known as a Receiver Autonomous Integrity Monitoring (RAIM) alert.

A typical standard RNP level for approach segments is 0.3 to 1.0, corresponding to a primary route width (centerline to boundary) of 0.3 nm to 1.0 nm. If the displayed RNP level falls below the limit, the FMS will generate a message that reads "DEGRADE," "UNABLE RNP," or something similar. Crews must immediately advise air traffic control (ATC) if this happens. Typically, a missed approach must be flown unless the landing can be completed in visual conditions.

With this higher level of GPS accuracy, approaches can be built to ease arrivals into airports with terrain or other obstacles that would otherwise make for challenging flying, especially at night or in instrument meteorological conditions (IMC). These approaches can include curvilinear segments, known as radius-to-fix (RF) legs. Special requirements come with flying such approaches, including adherence to speed limits that keep the aircraft within protected airspace and on the intended ground track.

Another important restriction is that crews cannot fly directly to a fix that starts, stops, or intercepts an RF leg. Doing so can put the aircraft well away from the intended ground track.

Put simply, an RNP procedure can make a difficult approach easy, but it must be set up and flown properly. Both the aircraft and the crew must be certified for RNP approaches. Some of the more demanding RNP procedures, such as those with an RNP level more restrictive than 0.3, can require specific authorization. They are labeled RNP (AR), indicating special authorization is required.

RNP Approach Minima

Pilots should check their operations specifications for the approach minima to use during an RNP approach. Typical approach charts list multiple lines of minima, which apply to various levels of aircraft equipment and certification. Those lines may include LNAV/Vertical Navigation (VNAV), Localizer Performance with Vertical Guidance (LPV), and Localizer Performance (LP).

Technique

Depending on aircraft type and configuration of the FMS and guidance panel, the acronym LAVAS can be used as a memory aid for important steps in setting up an RNP approach:

L - Select LNAV (or whatever guidance panel setting is used for FMS/GPS navigation).

A - Set the altitude of the final approach fix (FAF).

V - Select VNAV, or vertical navigation.

A - Arm the approach.

S - Check speed restrictions for radius-to-fix legs or any other approach segments.

Some operators' SOPs require an altimeter cross-check prior to the FAF, to ensure altimeter accuracy before beginning an approach with vertical guidance. Even if not specifically required, good airmanship would tend toward such a check.

Engine Restart in Flight: Guidance for Flight Crews

ThomasYoung — Mon, 13 Oct 2025 15:07:18 +0000

Engine Restart in Flight: Guidance for Flight Crews

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General

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SKYbrary

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SKYbrary

ENGINE AIR START IN FLIGHT

Discussion

This article provides general guidance for flight crews of turbine-powered aircraft on engine restarts in flight. Nothing herein supersedes aircraft-specific guidance in an operator's quick reference handbook (QRH), standard operating procedures (SOPs), or other official flight publications.

Under certain circumstances, pilots may elect to attempt a restart after an engine flames out in flight. Of course, if the situation makes it clear the engine is no longer airworthy, a restart is not advisable. Following a fire, overheat, oil loss, excessive fuel flow, or obvious mechanical malfunction, crews will secure the engine by closing off fluids and bleed air to minimize risk of further damage. Depending on the reason for the shutdown, this is normally accomplished by pulling the engine's fire handle, turning the ignition switch to OFF or STOP, or taking other steps to remove electrical power and close fluid valves. In the case of a turboprop engine, the condition lever will be moved to the FEATHER position.

Some aircraft manuals advise that if the engine flamed out for an unknown reason without obvious damage, crews may attempt a restart. Further guidance may state that if a condition such as heavy rain or turbulence is the suspected reason, crews may attempt a restart, ideally after the rain or turbulence has subsided. In some emergency situations, crews may need to attempt a restart even if they suspect damage, such as a flameout due to volcanic ash. (See the accident descriptions below.)

For many aircraft, the QRH makes the decision process easier by offering two different procedures: one for engine failure, which may lead directly to a a restart checklist, and one for engine fire, severe damage, or separation. In the latter case, of course, there will be no attempt at restart.

If an engine fails in level flight or in a climb, airspeed can deteriorate quickly unless the thrust lever for the operating engine is advanced. Crews in simulator training have been known to fixate on the air start and let speed decay. The pilot flying (PF) should prioritize flying the aircraft over assisting with the air start: Aviate, navigate, communicate.

In addition, crews should keep an eye on fuel balance. If the aircraft operates for long on one engine, fuel balance limits can be exceeded.

Engine Condition for Air Start

For most turbine engines, a good memory aid to help determine whether a restart is appropriate is the acronym V-O-R:

V: Vibration. Did you feel vibration before the engine failed? If the aircraft has vibration monitoring, did the instruments indicate out-of-limits vibration? If so, a restart may NOT be advisable.

O: Oil quantity. Does the oil quantity gauge indicate oil loss? If the aircraft has no oil quantity gauges, did the engine lose oil pressure? Is oil visible on the cowling? If there is any indication of oil loss, a restart is NOT advisable.

R: Rotation. Do the N1 and N2 gauges show that the engine core is windmilling? If there is no rotation at all, the engine has probably seized and will not restart.

In the case of turboprop aircraft, any propeller malfunction precludes an air start. A propeller that has lost hydraulic oil for pitch regulation could overspeed and potentially render the aircraft uncontrollable.

Air Start Limitations

Any given aircraft will have altitude and airspeed limitations pertaining to engine restart in flight. The QRH or other flight publications should include an airspeed and altitude envelope for windmilling starts and assisted starts.

Above a certain altitude, air starts will not be recommended. Typically, this altitude is 24,000 feet or higher. Below that limiting altitude, a chart or table of tabulated data will show the altitudes and speeds for windmilling starts, which rely on engine rotation due to ram air, and assisted starts, which use bleed air from an operating engine or from the auxiliary power unit (APU) to assist the starter. The data normally includes a minimum airspeed for air starts. This minimum speed, typically 250 or 300 knots, ensures adequate airflow to keep the engine rotating for a windmilling start.

If using APU bleed air to assist the start, as in the case of all engines flamed out, the APU's limiting altitude becomes a factor. With an all-engine flameout at high altitude, the aircraft may have to drift down below the maximum altitude for APU operation.

By the time the crew reaches this point in the decision-making process, they will have declared an emergency with air traffic control (ATC). ATC should be advised of the drift-down and any further crew intentions.

Pratt and Whitney JT3D engine on a Boeing 367-80 "Dash 80" (707 prototype). SKYbrary photo by Thomas Young, taken at the U.S. National Air and Space Museum's Steven F. Udvar-Hazy Center.

Air Start Procedures

With some aircraft, simply placing the thrust lever in the flight idle position will signal the full authority digital engine control (FADEC) to initiate an air start. If the aircraft does not have this capability, or if the auto-relight fails, crews will follow further QRH or SOPs to initiate an air start. This usually involves ensuring the above-mentioned altitude and speed limitations are met, then positioning the ignition and start switches for the air start.

If using bleed air to assist the start, the wing crossbleed valve may need to be opened unless the system's air start logic opens the valve automatically. Other bleed air loads, such as wing and engine anti-icing, may need to be turned off unless the system disables them automatically.

With turboprops, an air start depends on having adequate propeller oil to hydraulically move the propeller from the feathered position to the start position.

A successful air start will be indicated by rising turbine inlet temperature, oil pressure, and RPM. During this time, the pilot monitoring (PM) should watch for temperature exceedances and be prepared to terminate the start in the event of overtemperature, lack of oil pressure, or other malfunctions. (In most modern turbine aircraft, the FADEC will automatically terminate the restart if this happens. However, the crew should remain ready to intervene if necessary.) With many aircraft, the QRH will recommend letting the newly restarted engine warm up at flight idle before advancing the thrust lever, flight conditions permitting.

The final QRH steps for a successful air start will normally include directing the crew to move the transponder mode switch from TA ONLY back to TA/RA. (For an engine failure, procedures normally require selecting TA ONLY because an engine-out aircraft will not have the climb capability to respond to a climbing TCAS resolution advisory. With the engine restarted, this situation no longer obtains.)

Finally, even if the restart is successful and all systems look normal, the crew may want to consider a precautionary landing at the nearest suitable airport. Consulting with dispatch and maintenance via radio or ACARS can help inform this decision.

Emergency Air Start? Keep Trying

Three events, all involving Boeing 747s that entered volcanic ash, illustrate the importance of repeated attempts to restart failed engines in an emergency.

On June 24, 1982, a British Airways 747-236B encountered volcanic ash from an eruption of Mt. Galunggung, while flying 240 km southeast of Jakarta, Indonesia. The crew reported that St. Elmo's fire appeared on the windscreens, and "smoke" flowed from the floor vents. All four engines failed. According to the Aviation Safety Network (ASN), the aircraft began descending from 37,000 ft. After repeated attempts, the crew finally got engine #4 restarted at 13,000 ft, and restarted the other engines in succession. During efforts to restart the engines, the crew also dealt with pressurization loss, instrument malfunctions, and other complications. The #2 engine continually surged, so the crew shut it down. Despite visibility problems caused by ash abrasion of the windscreens, the crew made a safe emergency landing at Jakarta.

Approximately three weeks later, a Singapore Airlines 747-212B flew into volcanic ash from the same erupting volcano, while flying 110 nm southwest of Jakarta. According to the ASN report, the aircraft experienced multiple engine failures, and the crew landed on two engines at Jakarta.

On December 15, 1989, a KLM Royal Dutch Airlines flying near Anchorage, Alaska (U.S.) flew into what appeared to the crew as a normal-looking cloud at 25,000 ft. However, the cloud turned out to be volcanic ash from an eruption of Mt. Redoubt. Crew members reported seeing St. Elmo's fire on the windscreens and smelling a "sulphurous" odor. The ASN report says the crew added power to climb out of the cloud, but 10 to 15 seconds later, all four engines flamed out and the standby electrical system failed. After repeated attempts, the crew restarted the #1 and #2 engines while descending through 13,000 ft, and the other two engines restarted at 11,000 ft. The aircraft landed safety at Anchorage despite instrument malfunctions and other systems issues.

Although no one died in these events, all three were classified as accidents due to substantial aircraft damage.

Categories

General, Flight Technical

Electrical Problems: Guidance for Flight Crews

ThomasYoung — Thu, 25 Sep 2025 13:02:27 +0000

Electrical Problems: Guidance for Flight Crews

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Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Description

This article provides general guidance on electrical fires and other electrical malfunctions in transport-category aircraft The information herein does not supersede type-specific guidance in a company's Standard Operating Procedures (SOPs), Flight Operations Manual (FOM), Quick Reference Handbook (QRH), or other official publications.

Electrical Component Failure

In modern, highly automated aircraft, most electrical component failures do not cause the loss of electrical busses and the equipment powered by those busses. Typically, systems are designed so that if one generator fails, another generator picks up the load automatically. The QRH procedure may be as simple as disconnecting the failed generator from its constant-speed drive (CSD). Other malfunctions involve simple resets. The first step for a failed transformer-rectifier unit (TRU) may be to place the TRU switch to the OFF position, wait a few seconds, and then return it to the ON position.

When disconnecting a failed generator or resetting a failed TRU or inverter, it's always good crew resource management (CRM) to have the other pilot confirm that you have your hand on the correct switch. This avoids creating further problems by turning off an operating component.

System design usually isolates faults automatically, so that a malfunctioning generator or other component cannot damage other equipment with voltage interruptions or spikes. In previous generations of aircraft, isolating a faulty electrical bus could require a flight engineer to pull circuit breakers or even physically remove current limiters from electrical panels.

However, even in the newest aircraft, some component failures such as failed power distribution assemblies can render equipment inoperable. QRH procedures will normally list the inoperable equipment associated with a given failure and describe the impact on aircraft performance. Although items such as thrust reversers and ground spoilers might be hydraulically powered, they are usually electrically controlled. Therefore, an electrical malfunction can cause loss of those items. This, in turn, can impact performance such as landing distance, and the QRH will include relevant performance data.

In these situations, crews will need information from multiple places within the QRH. The initial malfunction might direct crews to a list of affected equipment, then to an aircraft performance table, and then to a modified landing checklist. The flight deck of an emergency aircraft is not the place to read these procedures for the first time. Pilots should study their QRH during initial training and review it periodically.

In the event of serious electrical malfunctions, an auxiliary power unit (APU) can sometimes power the entire electrical system, and the QRH will provide relevant guidance. Some APUs have altitude and temperature limits, so the crew may have to descend before starting the APU and using its generator. After loss of a single engine-driven generator, crews should consider starting the APU in flight as a precaution. In this situation, the APU generator can serve as backup in case another generator fails.

If a modern transport aircraft loses all main generators, it goes into an emergency electrical configuration, and a ram air turbine (RAT) provides emergency power. A RAT consists of a small propeller or turbine that deploys into the relative wind and drives a small generator. In most electrical systems, the loss of essential AC and/or DC busses will trigger the RAT to deploy. RAT generators typically have a much lower capacity than engine-driven generators, so they will power only the most critical equipment. Pilots should know what equipment will work when the aircraft is powered only by the RAT. The list is usually short: perhaps one radio, one electrically powered hydraulic pump, standby flight instruments, partial flight deck lighting, and flap control. (Many, if not most, aircraft have a mechanical means of emergency landing gear extension.)

RATs often have airspeed limits. For example, the Embraer 170 RAT requires an airspeed of 130 knots to power the AC essential bus. To help ensure adequate airspeed, RAT deployment in the E170 limits flaps to a lesser position than normally used for landing. RAT operation is usually quite loud, and simulator training should help pilots prepare for the distraction and startle factor associated with RAT deployment.

When a RAT deploys, it needs a few seconds to spin up and begin producing power. To avoid complete power loss during the brief spinup period, aircraft batteries can power essential DC busses for a short time. Some aircraft are equipped with DC-powered inverters that can supply limited AC power during battery-only operation. Pilots should be aware that without any source of charging power such as a RAT generator, battery life can be very short--as little as ten minutes.

Emergencies that trigger the RAT, such as failure of all engines with the resulting loss of the engine-driven generators, are rare. Apart from engine failures, other malfunctions can cause loss of main generators. For example, an Airbus notice from March 2025 described events when A320-family aircraft lost generators due to worn components found inside their CSDs. The article described how worn CSDs can cause frequency regulation problems, and the article discussed preventive maintenance that could detect the problem in advance. In one case study, an A319 crew lost both generators but managed to reset them.

Battery thermal runaway can create an emergency. QRH procedures for a battery overheat often require landing at the nearest suitable airport. The U.S. Federal Aviation Administration (FAA) defines thermal runaway as "rapid self-sustained heating of a battery cell driven by a chemical reaction of the materials within the cell where energy is released in the form of light or heat." FAA Advisory Circular 120-80B, "Firefighting of General and High-Energy In-Flight Fires," says thermal runaway "is generally evidenced by a sharp increase in temperature and pressure and a drop in cell voltage."

QRH procedures for some electrical malfunctions may direct crew members to open or reset circuit breakers. Modern aircraft have electronic circuit breakers in addition to the standard pull-type thermal circuit breakers. Electronic breakers are controlled through the aircraft's multifunction control and display unit (MCDU), so flight crews should familiarize themselves with how to access the relevant MCDU pages.

Pilot paging through MCDU functions. (SKYbrary photo by Thomas Young.)

In many cases, minor electrical problems at the gate, such as nuisance engine indicating and crew alerting system (EICAS) messages, can be cleared by powering down the aircraft, waiting a few minutes, then re-powering the aircraft. This should be done under QRH guidance or instructions from maintenance.

Electrical Fire/Smoke in the Cabin or Flight Deck

FAA Advisory Circular 120-80B, referenced above, says indications of hidden electrical fires include:

Abnormal operation or disassociated component failures.
Tripped circuit breakers.
Hot spots on the floor, sidewall, ceiling, or other panels.
Fumes,
Visual sighting of smoke.

In some cases, crews may have no direct fire indication. A 2016 incident involving an Embraer 190 on a flight from Boston to Toronto provides a case in point. The autopilot disengaged, three of the five electronic flight displays went blank, and multiple electrical malfunction EICAS messages appeared. Eventually, the crew restored electrical power and landed safety. The report by the Transportation Safety Board of Canada (TSB) said an examination revealed substantial fire damage in an avionics compartment. The report said the fire resulted from an unidentified fluid that had come into contact with an alternating current bus bar. "Within 36 seconds of the initial fault, power was lost to all main bus bars, and as a result, the smoke detector in the recirculation bay and the recirculation fans lost power," the report said. Due to the loss of the smoke detector, the pilots received no fire warning.

Some QRH procedures for smoke of unknown origin inside the aircraft assume that the source is an electrical fire. For this reason, QRH guidance for smoke in the cabin and the guidance for an electrical fire often look similar. These procedures can involve a lengthy process of powering down an electrical bus, observing whether the smoke stops, and re-powering the bus if it is not the smoke source. Then the procedure calls for powering down another bus, and so on.

In this situation, as in any emergency, situational awareness and crew judgment become important. If a suitable airport is close by, an immediate landing could be a better option than continuing with a long checklist or QRH procedure.

If a suitable airport is not close, the crew must make every effort to identify the fire source. Following an electrical fire checklist or QRH procedure to the end requires close attention to each step in a moment when stress level and workload are high. Here again, this is not the time for a first reading of the procedure. Pilots should review the procedures for electrical fire and smoke elimination now and then, as these procedures can be complex. In simulator training, pilots have been known to lose their place in the procedure and take steps that are either inappropriate or redundant. Familiarity with the QRH can reduce this hazard.

The first step in an electrical fire checklist is typically a memory item: don oxygen mask/smoke goggles. Donning the mask can be disorienting if pilots have not practiced it. If a pilot wears glasses, the glasses can be knocked off. This makes a dangerous situation worse if a pilot must search for glasses in a smoke-filled flight deck. Even if a pilot does not wear glasses, the mask can limit peripheral vision. In addition, the use of interphone and radios through an overhead speaker, coupled with the hiss of oxygen, can become a barrier to communication. For all these reasons it's a good idea for pilots to practice donning the mask and to get more comfortable wearing it. The cruise phase of a long flight can be a good time for conscientious crew members to rehearse this step.

In the event of smoke or fumes in the aircraft, do not delay donning the mask. Delay can result in incapacitation. If the smoke and fume elimination procedure is not a required memory item at your operator, consider making it a personal memory item for yourself. Smoke can make it difficult to read a checklist or QRH. Know your flight deck's switchology well enough to find items such as the pressurization dump switch by feel.

When an electrical fire is identified and located, make sure flight attendants or other crew members fight the fire immediately and aggressively. Appendix D of AC 120-80B lists the time that various crews had from the first indication of fire to the time when the fire became catastrophically uncontrollable. The times range from seven to 26 minutes.

Know your aircraft. As suggested in the above-mentioned AC, crews should understand the volume of overhead, above-ceiling space in an aircraft to combat fires in that area. Know what panels and hatches can be opened to spray extinguishing agent into underfloor and sidewall compartments, as well.

For more detail, please see the SkyBrary article on electrical fires.

No-Flap Landings: Guidance for Flight Crews

ThomasYoung — Mon, 22 Sep 2025 20:03:37 +0000

No-Flap Landings: Guidance for Flight Crews

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Description

This article provides generalized guidance for flight crews when landing a transport-category aircraft with flaps failed in the up position, or at a lesser setting than normally used for landing. The information herein does not supplant type-specific guidance in a company's Standard Operating Procedures (SOPs), Flight Operations Manual (FOM), Quick Reference Handbook (QRH), or other official publications.

A number of malfunctions can cause flaps to fail in the up position or close to the up position. These include an asymmetric flap condition that causes the asymmetry sensors to stop flap movement. Other possible causes include hydraulic failure, electrical failure, or mechanical failure such as a broken jackscrew. A no-flap landing is usually considered an emergency due to significantly higher landing speeds, which require longer runways. The high landing speeds can also result in brake overheat or fire.

(SKYbrary photo by Thomas Young)

Techniques

Guidance in SOPs and emergency procedures checklists usually recommend a long, straight-in approach. This reduces workload and minimizes maneuvering the airplane in a configuration with a higher stall speed. For these same reasons, it's also a good idea to ask Air Traffic Control (ATC) for a straight-out missed approach in the event of a go-around.

QRH guidance for flap failure will normally include landing performance tables that provide the proper approach speeds and expected landing distances. Crews should make sure to compare the performance data with runway available, and consider alternate landing sites if necessary. The QRH may leave it up to the crew whether to declare an emergency. Doing so can provide extra margins of safety, such as rescue and firefighting services (RFFS) standing by in the event of a brake fire.

When flying an approach with inoperative flaps, crews will not make the usual configuration callouts during the approach, i.e., "flaps one," "flaps two," etc. As a result, they may not have the usual cues for lowering the landing gear. Good crew resource management (CRM) can become a defence against this hazard. For example, during the approach briefing, the pilot flying (PF) might say, "Because we are not on our usual landing profile, let's take care not to forget to lower the landing gear." Of course, the landing gear aural warning would alert the crew below a certain altitude, but this would require a go-around in an already stressful situation.

Another hazard with a non-standard approach profile is forgetting to slow to approach speed (Vapp). Crews in simulator training have been known to fly the entire no-flap approach at 210 knots or higher. This negates landing performance calculations, increases the risk of a runway overrun and/or brake fire, and, at best, results in a go-around. A good approach briefing as described above can serve as a safety net against this hazard.

With some aircraft, a no-flap approach flown on a standard three-degree glide path may trigger a "sink rate" alert from the Enhanced Ground Proximity Warning System (EGPWS). Here again, a good approach briefing that notes this possibility can prevent the resulting startle factor during a critical phase of flight.

The QRH may require landing with autothrottle/autothrust (AT) off. Even if the QRH does not mandate this, turning off AT could be a good technique, to prevent large undesired power reductions as the aircraft nears the ground.

If the aircraft is equipped with autobrakes, crews should consider whether to use them, and if used, which setting to use. Autobrake systems have selectable deceleration rates. The QRH or other operator guidance may specify autobrake settings. Maximum manual braking may result in shorter landing distances than with autobrakes. Depending on landing distance available, the risk of brake overheat must be weighed against the greater risk of runway overrun.

At a higher landing speed, without the drag created by flaps, the aircraft will have a tendency to float in ground effect. Excessive flare could cause ballooning, which could turn a stable approach into a dangerous unstable approach. Most QRH guidance will direct pilots to "fly" the aircraft all the way into the touchdown with minimal flare.

After landing, crews should check brake temperatures and request RFFS assistance if necessary. If brake fire appears imminent, crews should consider preparing for an emergency evacuation. With high brake temperatures, crews should also consider keeping the aircraft away from the gate area until brakes have cooled. RFFS may have better access to the aircraft if it's on a taxiway or runway rather than at a gate with other aircraft and equipment close by.

Categories

General, Flight Technical

Announcements to Passengers During Emergency or Non-Normal Operations: Guidance for Flight Crews

ThomasYoung — Tue, 10 Jun 2025 14:24:34 +0000

Announcements to Passengers During Emergency or Non-Normal Operations: Guidance for Flight Crews

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Definition

This article provides guidance on briefing passengers during emergency and abnormal operations. The content is derived from flight crew experience and is general in nature. Nothing herein supersedes a company's Standard Operating Procedures (SOP), Flight Operations Manual (OM), or other official guidance.

Background

A small segment of the population fears flying under any circumstances. Other passengers who do not normally fear flying might become more nervous in the aftermath of a highly publicized accident or incident. During an aircraft emergency, their understandable lack of aviation knowledge may cause them to imagine the worst. Time and workload permitting, flight crews can counter this with information. In simple terms, the more you talk to your passengers, the less they will worry.

Pilots are taught that during emergencies, they should aviate, navigate, and communicate -- in that order. And communication with Air Traffic Control (ATC) and crew members naturally takes priority over PA announcements to passengers. But as long as safety permits, informative announcements to passengers can reassure them and even help prevent passenger disturbances.

Tell Them What HAS Happened

Tell passengers what has happened, and be specific. For example, if you lose a hydraulic system and you say, "We have a systems problem," the vagueness may create more anxiety than it relieves. But if you say, "We have lost one of the hydraulic systems that lower the landing gear, but we still have another system to get the gear down," passengers should understand that there is no danger.

Often, when passengers complain about a situation with an airline, they say they weren't given enough information, or even that they were kept in the dark. Seldom do they complain about too much information.

Try to remember that aviation terminology can confuse or frighten the uninitiated. "Flameout," may sound like a fire rather than an engine failure. "Bingo fuel" may sound like running completely out of fuel rather than the fuel level at which you must leave holding.

Tell Them What IS Happening

Are you in a holding pattern? Tell them why. Are you burning off fuel to get down to landing weight? Explain that. Are you on the ground in a hold pad, under clear skies but waiting for a thunderstorm to move away from your planned route? Describe how the issue is en route weather, even though the weather they can see out their windows looks good. Are you in continuous light to moderate chop with no smoother altitude available? Reassure the passengers that the aircraft is built to withstand far worse.

Have the passenger oxygen masks dropped? Time permitting, explain why that took place. Is that pressurisation leak causing a whistling noise? The passengers might be relieved to know it's only air escaping around a seal, with little effect on cabin pressure. Mist flowing from the environmental control system's gaspers on a hot, humid day -- something completely normal -- might be mistaken for smoke by a nervous traveler.

Tell Them What IS GOING to Happen

Are you performing a ground reset procedure that requires you to power down the aircraft to clear an electrical problem? Don't surprise the passengers by putting them in the dark without warning them. Do you need deicing? Inexperienced travelers might not understand why they see trucks moving around the aircraft.

Are you diverting to an alternate? Describe why that's the safer option. Will crash trucks be standing by? Explain that it's a routine precaution. Do circumstances such as a short runway or a gusty crosswind require a relatively firm touchdown? Give the reason.

After landing, will emergency personnel inspect the aircraft before it taxis to the gate? Once at the gate, will medical or law enforcement personnel board the aircraft? If so, advise the passengers to expect that.

Tell Them What IS NOT Going to Happen

Nervous passengers may worry about whether the landing will be safe, regardless of the nature of the emergency. You may be diverting for an avionics overheat, for example, which has nothing to do with landing the aircraft. But the uninitiated still might envision sliding off the end of the runway. If the malfunction does not affect landing performance, tell them so.

If you're diverting to an alternate and do not have an assigned gate, advise passengers that the aircraft will probably not taxi directly to the terminal.

Repetition Does Not Hurt

No new information? Even if you simply repeat what you told the passengers 20 minutes ago, they will know you haven't neglected to keep them informed.

Categories

General, Emergency and Contingency

Fuel - Calculating Holding Fuel Endurance: Guidance for Flight Crews

ThomasYoung — Tue, 03 Jun 2025 18:19:42 +0000

Fuel - Calculating Holding Fuel Endurance: Guidance for Flight Crews

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Definition

This article provides flight crews with general guidance on calculating holding fuel endurance. The limit of that endurance is sometimes called "bingo fuel." That is the fuel level at which an aircraft must depart holding and fly either to the filed destination or to an alternate airport. Nothing herein supersedes Aircraft Flight Manual (AFM) guidance or other official publications for a given operator and/or aircraft.

The description below assumes that the flight crew has a dispatch release with a computer flight plan that includes the expected fuel burn from waypoint to waypoint. Even though some Flight Management Systems (FMS) can calculate holding fuel endurance, it is always a good technique to back up the FMS with manual calculations, in case of data entry error or equipment failure.

The numbers used in the description below are for a generic aircraft. Typical numbers for a specific aircraft on a specific route may be quite different.

Description

To calculate bingo fuel for holding, the pilot must begin by adding four figures:

Fuel burn from the holding point to the destination
Fuel to reach the alternate
Fuel to fly an approach
Required fuel reserve

(For detailed definitions of alternate fuel and reserve fuel, please see the article Fuel - Flight Planning Definitions.)

Alternate fuel and reserve fuel should be provided by the dispatch release. Fuel to fly the approach should be provided by the dispatch release or published in the AFM or company manuals. To calculate the first item, fuel burn from the holding point to destination, add the expected fuel burn for each waypoint from the holding point to the destination. If the computer flight plan lists the planned fuel on board at each waypoint, take planned fuel at the waypoint where you began holding, and subtract from that figure the planned fuel on board at destination. That will give you the figure for fuel to reach the destination.

If you are holding at a point NOT on your flight plan, you will have to calculate destination fuel by other means. The FMS can normally provide this figure. If not, AFM guidance may include a rough estimate for typical fuel burn. For example, if the AFM says typical burn at a given altitude is 1,000 pounds of fuel for every 100 miles, and the destination is 152 miles away, then fuel to reach the destination is 1520 pounds.

For demonstration purposes, we will use the following example:

Fuel burn from holding point to destination: 1520 pounds. (Calculated by FMS or crew)
Alternate fuel: 2200 pounds. (Provided on the release)
Approach fuel: 400 pounds. (Provided in company publications)
Required fuel reserve: 2000 pounds (Provided on the release in accordance with regulations)

1520+2200+400+2000=6120 pounds.

When fuel quantity on board reaches 6120 pounds, the aircraft must depart holding and fly either to the destination or to the alternate airport. Air Traffic Control (ATC) will want to know how long the aircraft can hold, and they need this fuel endurance expressed in TIME rather than fuel quantity.

To calculate maximum holding time, check fuel quantity on board and subtract from that figure your number for bingo fuel. For demonstration purposes, we will say the aircraft has 8,342 pounds of fuel on board. 8342-6120=2,222 pounds. Therefore, you can burn 2,222 pounds of fuel before you must leave holding.

To convert this figure to a time, check the aircraft's fuel flow. Make sure to do this after the aircraft is established in the hold at the planned holding speed. For demonstration purposes, we will say this is a two-engine aircraft, and both fuel flow gauges show 1200 pounds per hour. This means both engines taken together are using 2400 pounds per hour. Divide 60 into 2400, and you will see that the aircraft is burning 40 pounds per minute. Divide 2,222 by 40, and you will see that you can hold for 55 minutes.

What If I Don't Have An Alternate?

A flight crew can find itself in holding even when destination weather is good enough not to require an alternate airport. An accident or incident can close a runway at the destination. Unforecasted bad weather may appear, especially in climates where thunderstorms can form quickly during the summer. Any number of problems can create a need for holding.

If you do not have an alternate, you calculate holding endurance in the same way described above, except of course you will not have alternate fuel. You would begin the process by adding the other three figures: fuel to destination, required reserve, and approach fuel.

In this case your time available for holding is likely to be very limited. Be prepared to declare "minimum fuel" as the situation requires.

Categories

General

Lighting Control Systems

Plamen Georgiev — Thu, 30 Nov 2023 08:14:20 +0000

Lighting Control Systems

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Description

Lighting control systems provide air traffic controllers with means to manage the aerodrome lights.

Typical features found in Lighting control systems include:

Standard configurations. This feature allows the controller to activate all relevant lights for a pre-defined situation with a single button. Such situations are e.g. "daytime", "nighttime good visibility", "reduced visibility XXX metres", etc.
Runway switching. Somewhat related to the standard configurations, this feature allows the controller to quickly apply the relevant settings to a different runway (most often the opposite direction)
Light intensity adjustment for a particular type of light (e.g. approach, runway, TDZ, VASIS, etc.), e.g. when a pilot requests the controller to dim it. This feature also allows manual switching of all relevant lights as an alternative to a standard configuraiton. It can be used for troubleshooting or in case standard configurations cannot be activated for some reason.
Stop bar management
Release of control. This feature enables other personnel to operate the lighting system and prevents the controller from using it. This is done for maintenance purposes.
Emergency signals. The aerodrome lighting system can be used in emergency conditions or when light signals are not observed. Flashing runway or taxiway lights is an instruction to vacate the runway and observe the tower for light signal. This can be a separate feature or performed as a manual light adjustment.
Provision of troubleshooting information, such as failure of a particular set of lights.

The control panel of a lighting control system can take various forms, e.g.:

toggle or rotary switches with labels. These are simple and cost-effective to implement and are often used at smaller aerodromes.
"facsimile" panels which combine a graphical representation of the aerodrome layout with buttons at appropriate points.
touchscreen panels which are effectively computer monitors. This option can provide the most customizable and convenient user interface.

Example of a control panel with switches:

Example of a facsimile control panel:

Hindsight 35

steven.shorrock — Mon, 25 Sep 2023 14:35:08 +0000

Hindsight 35

Article Information

Category:

General

Content source:

EUROCONTROL

Content control:

SKYbrary

HindSight 35

Download the full HindSight 35 magazine here

Published in September 2023, HindSight 35 focused on the theme of Just Culture...Revisited.

Welcome

Welcome to issue 35 of EUROCONTROL’s HindSight magazine, the magazine on human and organisational factors in operations, in air traffic management and beyond.

This issue is on the theme of Just Culture…Revisited. Once again you will find a diverse set of articles from a diverse set of authors in the context of aviation, maritime, rail and healthcare. The articles reflect Just Culture at the corporate and judicial levels from the perspectives of personal experience, professional practice, theory, research, regulation, and law.

At the heart of HindSight magazine is the idea that we can and should learn from multiple perspectives. Especially for topics such as Just Culture, there can be tensions between these perspective, which are opportunities for learning and growth. There are differences between the perspectives of front-line staff, safety specialists, legal experts, managers, and social scientists, and senior managers, and of course citizens. What is ‘just’? How should we conceptualise Just Culture? How should we design and implement regulations, policies and protocols relating to Just Culture? What gets in the way of Just Culture? More than most other topics, this is one that can arouse strong feelings and opinions.

In this issue, leading voices from the ground and air share perspectives on these questions. It is also recommended to review issue 18 of HindSight on Justice & Safety. The two issues together offer a rare and comprehensive set of insights.

Special thanks are extended to the authors and the operational reviewers, who help to ensure that HindSight magazine is relevant, interesting and useful. While the primary readers are operational staff, especially those involved in aviation, it is read much more widely, by different people in different sectors, especially those where safety and business continuity is critical.

We hope that the articles trigger conversations between you and others. Do your operational and nonoperational colleagues know about HindSight? Please let them know. Search ‘SKYbrary HindSight’ for all issues, covering a wide variety of themes.

HindSight 35 Articles

Reflections on Just Culture

Just Culture in Practice

Artificial Intelligence

Legal and Judicial Perspectives

Views from Elsewhere

Human Performance in the Spotlight

Human performance in the spotlight: ‘Human error’ and ‘honest mistakes’, by Steven Shorrock

Diversity and Inclusion

Diversability and restorative Just Culture, by Milena Bowman

In Conversation

From cockpits to courtrooms: Looking back on a 50-year journey. A conversation with Tom Lintner, by Steven Shorrock

The Lighter Side

Cartoons, by Daniel Avram

All Formats of HindSight 35

See all editions of HindSight magazine

Categories

General

North Atlantic Operations - Communications

Plamen Georgiev — Sun, 30 Apr 2023 09:43:44 +0000

North Atlantic Operations - Communications

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Description

The airspace of the North Atlantic (NAT), which links Europe and North America, is the busiest oceanic airspace in the world. In 2012 approximately 460,000 flights crossed the North Atlantic and that volume of traffic continues to increase. Direct Controller Pilot Communications (DCPC) and ATS Surveillance are unavailable in most parts of the NAT Region. Aircraft separation, and hence safety, are ensured by demanding the highest standards of horizontal and vertical navigation performance/accuracy and of operating discipline.

This article is intended to provide an overview of the communication equipment requirements and applicable procedures for the NAT region.

Voice Communication

Electromagnetic waves in the VHF band propagate in a straight line. Due to the earth curvature, it is often not possible to use it for communicaiton in some parts of the oceanic airspace. Therefore, alternative solutions need to be employed, e.g.:

HF communication, which is based on ground waves (that are emited horizontally and follow the earth curvature) or sky waves (that are emited at a high angle and bounce back when reaching the ionosphere).
Satellite communicaiton.

Operations in the NAT outside VHF coverage require the carriage of two long range communication systems, one of which must be HF. The second one can be SATVOICE or CPDLC provided that the coverage criteria are met. For example, this is not the case with Inmarsat CPDLC or SATVOICE system when operating north of 80N.
In certain situations waivers from the HF requirement can be requested, e.g. if the system is unserviceable and the aircraft is returning to the base for repairs. This is subject to approval from the area control centre (ACC) serving the route of flight provided the aircraft has at least two other appropriate long-range communication systems.

Routine air-ground voice communications in the NAT region are conducted via aeronautical radio stations staffed by radio operators who are not air traffic controllers. The operators relay messages between the aircraft and the relevant oceanic ACC (note that CPDLC communicaiton is conducted directly between the air traffic controller and the aircraft). There are six radio stations in the NAT: Bodø Radio (Norway), Gander Radio (Canada), Iceland Radio (Iceland), New York Radio (USA), Santa Maria Radio (Portugal) and Shanwick Radio (Ireland). Radio stations are also responsible for the operation of General Purpose VHF (GP/VHF)
outlets.

Radio operators usually maintain a continuous watch on more than one frequency therefore it is useful for flight crews to state the frequency used when placing their initial call.

Reykjavik centre operates a number of VHF stations in Iceland, Faroe Islands and Greenland. They provide tactical procedural control and ATS Surveillance services. The callsign used is "Reykjavik Control" (or just "Reykjavik") and indicates that the flight crew is communicating directly with an air traffic controller. Note that the callsign "Iceland radio" refers to the radio station manned by a radio operator who is only relaying messages.

SELCAL

Flight crews must maintain a continuous watch on the assigned frequency unless SELCAL equipped. In this case they should follow the following procedures:

provide the SELCAL code in the flight plan (note that if the aircraft for a flight needs to be changed, either a new FPL or a CHG message must be filed containing the new registration and SELCAL code)
perform a SELCAL check at or prior to entry into oceanic airspace
maintain a SELCAL watch after successfully completing the SELCAL check

Complying with these procedures is important even when SATVOICE or CPDLC are being used for routine air-ground communications as this ensures that ATC has a timely means of contacting the aircraft.

SELCAL code assignment is predicated on the usual geographical area of operation of the aircraft. Therefore, in order to avoid duplication issues, the operator should contact the SELCAL Registrar and request an appropriate SELCAL code if flying beyond the area of normal operations.

SATVOICE

The Aeronautical Mobile Satellite (Route) Service, more commonly referred to as SATVOICE, can be used as a supplement to HF and CPDLC. The necessary phone numbers (of both radio stations and ACCs) can be found in the State AIPs. Since oceanic traffic typically communicates with ATC through radio facilities, routine SATVOICE calls should be made to such a facility rather than the ACC. Only when the urgency of the communication dictates otherwise should SATVOICE calls be made to the ACC. Note that HF propagation difficulties do not constitute urgency.

The use of SATVOICE is described in ICAO Doc 7030 (Regional Supplementary Procedures). The provisions include that even when using SATVOICE, flight crews must simultaneously operate SELCAL or maintain a continuous watch on the assigned frequency.

Data Link Communications

Data link communications are used for position reporting (via ADS-C and CPDLC) and ATC communications using FANS 1/A CPDLC. CPDLC provides communication redundancy and controllers will in many cases use it even though the flight crew is maintaining a continuous watch on a direct controller-pilot VHF frequency. ADS-C furthermore enables ATC to perform route conformance monitoring for downstream waypoints.

The aircraft data link system provides indication of any degraded performance which results from a failure or loss of connectivity. The flight crew should then notify the ATS unit as soon as practicable. Timely notification is essential to ensure that the ATS unit has time to assess the situation and apply a revised separation standard, if necessary.

Similar to SATVOICE usage, flight crews electing to use Data link communications remain responsible for operating SELCAL, or maintaining a continuous on the assigned HF frequency.

Flights equipped with CPDLC and/or ADS-C should ensure that they are logged on to the appropriate oceanic ACC. This applies even when the aircraft is provided with ATS Surveillance services. With the introduction of PBCS separation, establishing and maintaining a data link connection becomes even
more important since an active data link connection is one of the requirements for the application of the separation.

Inter-pilot Frequency (123.450) and Emergency Frequency (121.5)

The frequency 123.450 MHz has been established for world-wide use when aircraft are out of range of VHF ground stations. It is intended for pilot-to-pilot exchanges of operationally significant information and is not to be used as a "chat" frequency. In case of air-ground communicaions failure, 123.450 MHz may be used to relay position reports via another aircraft.

The inter-pilot frequency (123.450 MHz) may also be used by flight crews to contact other aircraft when needing to coordinate offsets required in the application of the Strategic Lateral Offset Procedures (SLOP).

The emergency frequency (121.5 MHz) should be continuously monitored by all aircraft so as to be prepared to offer assistance to any other aircraft advising an emergency situation.

If necessary, initial contact for relays or offset coordination can be established on 121.5 MHz. Note that great care must be exercised in such cases as this frequency could be used by aircraft experiencing or assisting with an ongoing emergency. In order to minimise unnecessary use of 121.5 MHz, it is recommended that when possible aircraft additionally monitor 123.450 MHz.

Flight Level Allocation Scheme (FLAS)

Plamen Georgiev — Sun, 30 Apr 2023 09:39:02 +0000

Flight Level Allocation Scheme (FLAS)

Article Information

Category:

General

Content source:

SKYbrary

Content control:

SKYbrary

Definition

Flight Level Allocation Scheme (FLAS). The scheme whereby specific flight levels may be assigned to specific route segments within the route network.

Source: ICAO EUR Doc 009: Guidance material on the implementation of a 300 m (1000 ft) vertical separation minimum in the European RVSM airspace

Description

The flight level allocation scheme (FLAS) sets out the main principles of flight level allocation within a portion of airspace, or at the border between two airspaces.

FLAS is described in relevant documents, such as Letters of agreement between ATS units, AIPs, AIMs, etc. The tactical application of similar solutions (e.g. temporary use of opposite flight levels after coodination between two controllers from different units) is not considered as FLAS. The goal of FLAS is to establish basic, robust rules to be followed in order to achieve safe operations in terms of vertical separation. The controllers may, after a successful coordination, deviate from the FLAS (e.g. regarding a particular flight, for a period of time, etc.).

Applications of FLAS include:

Allocation of levels along the border between two ATS units. While the standard allocation of cruising levels, set out in Annex II (i.e. odd levels eastbound, even levels westbound) is considered inappropriate, the two neighbouring units may agree upon an alternative, e.g. Unit A transfers traffic at odd levels and Unit B uses even levels.
Allocation of specific levels (or level bands) for certain situations. These are often defined for aircraft departing from or arriving to an aerodrome that is close to the boundary. Normally, the FLAS will be constructed in such a way as to ensure vertical separation between departures and arrivals in case of radio communication failure. Normally, arriving aircraft would be cleared to a level that is above the one assigned for the departures. Crossing the other aircraft's level would only be cleared after successfully establishing communicaiton and when there is reasonable certainty that horizontal separation would be maintained until the two aircraft are vertically separated again. The level assignment does not necessarily follow the eastbound/westbound standard. Examples:
- Arrivals to XXXX are to be passed to Approach at level XXX (or within the level band between XXX and YYY)
- Departures from XXXX are to be passed to Area Control at level XXX (or below level XXX or within the level band between XXX and YYY)
- Arrivals to XXXX are to be passed to the next Area Control Unit (within which XXXX is situated) at levels below XXX (or within the level band between XXX and YYY)
Level allocation based on time of day. For example, flights over the North Atlantic are normally eastbound in the morning and westbound in the afternoon. Therefore, both odd and even levels are normally available for flights in the prevailing direction. This principle can be applied whenever the flow of traffic follows similar daily routines to increase the number of available levels.
Allocation of levels at the border between RVSM and non-RVSM airspace
Contingency FLAS (often abbreviated as cFLAS). An example of this is the temporary suspension of RVSM operations due to a wide area affected by severe turbulence. In such case, neighbouring ATS units may agree to the use of the available levels (e.g. Unit A would use FL 310, FL 350 and FL 390 and Unit B would use FL 330m FL 370 and FL 410). Having appropriate arrangements in place (e.g. written down in a Letter of agreement) would ease the transition process in such situations.

Categories

General, Loss of Separation

General

Required Navigation Performance (RNP) Approaches: Guidance for Flight Crews

Required Navigation Performance (RNP) Approaches: Guidance for Flight Crews

Definition

Description

RNP Approach Minima

Technique

Further Reading

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Engine Restart in Flight: Guidance for Flight Crews

Discussion

Engine Condition for Air Start

Air Start Limitations

Air Start Procedures

Emergency Air Start? Keep Trying

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Electrical Problems: Guidance for Flight Crews

Description

Electrical Component Failure

Electrical Fire/Smoke in the Cabin or Flight Deck

Further Reading

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No-Flap Landings: Guidance for Flight Crews

Description

Techniques

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Announcements to Passengers During Emergency or Non-Normal Operations: Guidance for Flight Crews

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Definition

Background

Tell Them What HAS Happened

Tell Them What IS Happening

Tell Them What IS GOING to Happen

Tell Them What IS NOT Going to Happen

Repetition Does Not Hurt

Related Articles

Fuel - Calculating Holding Fuel Endurance: Guidance for Flight Crews

Fuel - Calculating Holding Fuel Endurance: Guidance for Flight Crews

Definition

Description

What If I Don't Have An Alternate?

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Lighting Control Systems

Lighting Control Systems

Description

Further Reading

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Hindsight 35

Hindsight 35

Welcome

HindSight 35 Articles

Welcome

Forewords

Editorial

Reflections on Just Culture

Just Culture in Practice

Artificial Intelligence

Legal and Judicial Perspectives

Views from Elsewhere

Human Performance in the Spotlight

Diversity and Inclusion

In Conversation

The Lighter Side

Other Content

All Formats of HindSight 35

North Atlantic Operations - Communications

North Atlantic Operations - Communications

Description

Voice Communication

SELCAL

SATVOICE

Data Link Communications

Inter-pilot Frequency (123.450) and Emergency Frequency (121.5)

Further Reading

Related Articles

Flight Level Allocation Scheme (FLAS)

Flight Level Allocation Scheme (FLAS)