This article provides mainly guidance for tower/approach controllers on what to expect from an aircraft experiencing the effects of a brake problem and some of the considerations which will enable the controller, not only to provide as much support as possible to the aircraft concerned, but also maintain the safety of other aircraft at or in the vicinity of an aerodrome and of the ATC service provision in general.
Useful to Know
Malfunctions or human errors related to application of brakes on landing and during taxi, but also during rejected take-offs, have been the cause of numerous accidents and incidents (See "Accidents and Incidents" section). Distraction, preoccupation and technical malfunction during the landing sequence as well as during rejected take-offs play a prominent role in many occurrences which result in overheated brakes and brake failures which subsequently involve increased levels of risk related to deceleration and directional control.
There are various configurations of brake equipped undercarriage or main landing gear. Aircraft brakes are located on the main wheels and are usually selected by foot pedals but on some older aircraft types may be selected by hand controls. On most modern transport aircraft autobrake and anti-skid systems are provided. (For more information, see the dedicated article on aircraft brakes in SKYbrary.)
Because brake and antiskid failures are often a direct consequence of hydraulics related problems or from faults in associated electrical/electronic control units, the flight crew may become aware of the emerging brake malfunction rather late into the flight, e.g. when they set up the autobrake system during their approach preparation. These systems are normally not needed during the cruise phase and because of that, the problem may not be relayed to ATC until the beginning of approach.
Listed are some braking and deceleration issues that directly affect the aircraft performance:
- Overheated brakes - The kinetic energy lost by slowing an aircraft down is usually translated into heat by friction and could result in:
- Loss of braking performance
- Tyre deflation / tyre burst
- Braking without or partial antiskid-protection
- significantly increased landing distance required
- tyre deflation / tyre burst
- aircraft controllability issues
Brake failure and subsequent poor deceleration or degraded directional control in turn could result in:
Anticipated Impact on Crew
A wide range of practical problems could arise following brake related problems:
- High level of stress and increased workload - caused by directional control and deceleration problems resulting from brake failure during landing, or during high speed rejected take off (RTO);
- Lack of awareness - Crew might be not aware of fire, tyre burst or deflation that could result from heavy braking upon landing, RTO, or of smoke coming from the undercarriage;
- Request fire and rescue services - hot brake incidents could be considered by the crew a reason to request attendance of fire and rescue;
- Decision for emergency evacuation - the cockpit crew could take the decision for emergency evacuation if fire is detected following a high energy brake application
Suggested Controller’s Actions
What to Expect
As a controller, expect:
- Pilots, if aware prior landing of the brake problem, to request:
- the longest runway available;
- the widest runway available whenever directional control problems on the ground are anticipated;
- to execute holding procedures for thorough approach briefing and procedure review as well as to burn fuel and minimise weight;
- to divert to alternate aerodrome if any condition such as poor braking action, runway contamination or adverse weather is present at the destination aerodrome or if any other conditions exist that could result in higher ground speed on touchdown or are unfavorable for taxi;
- to divert to alternate aerodrome depending on availability of maintenance personnel and respective technical facilities should the airplane need repair.
- Aircraft overrunning runway threshold at far end (stop end);
- Aircraft swerving off of the runway;
- Tyre burst and associated damage to the aircraft - inform the aircraft crew and the airport fire rescue services if a burst tyre was observed;
- Blocked runway after landing - plan ahead regarding pending departures and arrivals, possibly sequencing them for other runways if available.
What to Provide
Best practice embedded in the ASSIST principle could be followed (A - Acknowledge; S - Separate, S - Silence; I - Inform, S - Support, T - Time):
- A - acknowledge the emergency, inform the crew if fire/smoke is observed from the undercarriage area;
- S - separate the aircraft and if necessary prioritise it for landing, allow long final if requested, keep the active runway clear of departures, arrivals and vehicles;
- S - silence the non-urgent calls (as required) and use separate frequency where possible;
- I - inform the airport emergency fire rescue services and all concerned parties according to local procedures; as tower controller expect airport authorities to execute their emergency plan; inform the supervisor and other sectors/units concerned;
- S - support the flight by providing any information requested and necessary such as type of approach, runway length and aerodrome details, etc.
- T - provide time for the crew to assess the situation, don’t press with non urgent matters.
When informed about possible/actual brake problems for aircraft inbound to land, be ready to:
- Inform pilot about runway length and condition;
- When aircraft on final do not allow poor positioning for the approach, monitor carefully alignment, height, speed, distance from touchdown;
- Keep safety strip clear;
- Advise pilots of EMAS, if available
- Plan ahead the pending traffic, consider assigning priority to the arrivals if necessary due to possibility of blocked runway;
- Make arrangements for towing equipment to be on stand-by as appropriate;
- Request help of technical staff required to inspect and assess the damage to the aircraft as appropriate;
- If pilot reports vibrations during the take-off/landing roll - consider possible tyre burst/debris on the runway and make the necessary arrangements for runway inspection. Inform the pilot if tyre burst has occurred, especially important if it took place after take-off.
Additionally, as a ground controller consider coordinating where to position on the ground an aircraft that requires a prolonged brake cooling period following a hot brake incident to minimise the disruption to other traffic.
Accidents and Incidents
This section contains events where brake problems were experienced.
On 1 February 2015, a Bombardier CRJ 1000 departed from Pamplona with slush likely to have been in excess of the regulatory maximum depth on the runway. On landing at Madrid, the normal operation of the brake units was compromised by ice and one tyre burst damaging surrounding components and leaving debris on the runway, and the other tyre was slow to spin up and sustained a serious flat spot. The Investigation concluded that the Pamplona apron, taxiway and runway had not been properly cleared of frozen deposits and that the flight crew had not followed procedures appropriate for the prevailing conditions.
On 11 February 2017, a Cessna 402 failed to stop on the runway when landing at Virgin Gorda and was extensively damaged. The Investigation noted that the landing distance required was very close to that available with no safety margin so that although touchdown was normal, when the brakes failed to function properly, there was no possibility of safely rejecting the landing or stopping normally on the runway. Debris in the brake fluid was identified as causing brake system failure. The context was considered as the Operator s inadequate maintenance practices and a likely similar deficiency in operational procedures and processes.
On 15 December 2014, the Captain of a Saab 2000 lost control of his serviceable aircraft after a lightning strike when he attempted to control the aircraft manually without first disconnecting the autopilot and despite the annunciation of a series of related alerts. The aircraft descended from 4,000 feet to 1,100 feet at up to 9,500 fpm and 80 knots above Vmo. A fortuitous transient data transmission fault caused autopilot disconnection making it possible to respond to EGPWS 'SINK RATE' and 'PULL UP' Warnings. The Investigation concluded that limitations on autopilot disconnection by pilot override were contrary to the type certification of most other transport aircraft.
On 9 January 2006, a Mc Donnell Douglas MD83 being operated by Spanair on a scheduled passenger flight from Bilbao to Barcelona made an unstablised day VMC approach to a dry runway 07R at destination and landed long with apparently locked brakes before coming to a stop 140 metres from the end of the 2660 metre long runway. Following ATC reports of a fire in the area of the left main landing gear, an evacuation was ordered using the right side doors during which five of the 96 occupants received minor injuries. The RFFS arrived at the scene during the evacuation and extinguished the fire. Significant damage occurred to both main landing gear assembles and to both wings and the tail assembly but there was no damage to the primary structure.
On 1 March 2005, a Boeing 777-200 being operated by Pakistan International Airlines on a scheduled passenger flight from Lahore to Manchester experienced a landing gear fire during taxi in at destination after an apparently routine landing in normal day visibility. There were no flight deck indications of a significant fire but an emergency evacuation was recommended by attending Fire Crew and carried out. Thirty one of the 344 occupants sustained minor injuries during this evacuation and the rest were uninjured. Five firefighters also sustained minor injuries as they assisted passengers from the slides. Damage to the aircraft was minor.
On 24 August 1999, a Boeing 767-300 being operated by SAS on a scheduled passenger flight from Copenhagen to Tokyo was unable to get airborne from the take off roll on Runway 22R in normal daylight visibility and made a rejected take off from high speed. The aircraft was taxied clear of the runway and after a precautionary attendance of the RFFS because of overheated brakes, the passengers were disembarked and transported to the terminal. There was minor damage to the aircraft landing gear and rear fuselage.
On 18 June 1998, the crew of a Swearingen SA226 did not associate directional control difficulty and an extended take off ground run at Montreal with a malfunctioning brake unit. Subsequent evidence of hydraulic problems prompted a decision to return but when evidence of control difficulties and fire in the left engine followed, a single engine diversion to Mirabel was flown where, just before touchdown, the left wing failed upwards. All occupants were killed when the aircraft crashed inverted. The Investigation found that overheated brakes had caused an engine nacelle fire which spread and eventually caused the wing failure.
- ^ *Burst tyre - Even though modern aircraft rely on a number of defences to prevent tyre burst (e.g. nitrogen inflation, anti-overheat thermal fuses), such incidents are not uncommon. The burst tyre incidents are associated with various circumstances, brake related problems are among them. The explosive tyre burst could inflict serious structural damage with associated consequences such as fuel leaks (see CONC, vicinity Paris Charles de Gaulle France, 2000), even cause explosive engine failure due ingestion of tyre debris.