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Landing Gear Problems: Guidance for Controllers

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Category: Runway Excursion Runway Excursion
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

There is no set of ready out-of-the-box rules to be followed universally. As with any unusual or emergency situation, controllers should exercise their best judgment and expertise when dealing with the apparent consequences of brake related problems and the possible outcomes. A generic checklist for handling unusual situations is readily available from EUROCONTROL but it is not intended to be exhaustive and is best used in conjunction with local ATC procedures.

Contents

Description

This article provides guidance for tower/approach controllers on what to expect from an aircraft experiencing the effects of landing gear problems 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

Hard, non-retractable landing gear was common in the early days of aviation but is only now seen on light aircraft. Commercial airliners use complex retractable undercarriages with multi-step automated extraction procedures, and various systems to provide redundancy and control. One such system provides easily recognisable light indication regarding the status of the landing gear. The principle is simple - green light when the landing gear is down and locked and red light when there is a discrepancy between the gear lever and landing gear positions. The unsafe indication might be the first sign of a problem related to the proper preparation of the landing gear for landing. Depending on the aircraft type and landing gear retraction system, the exact nature of the problem may vary significantly.

Due to the variety of modern aircraft landing gear design, it could be quite hard for a non-professional to distinguish between normal and abnormal gear operation. In the case of a partial extension the visual inspection should be done only by a qualified professional.

Effects

Landing with main/nose gear that might not be locked/fully extended could result in:

  • Gear-up landing;
  • Landing with partially extended undercarriage;
  • Gear malfunction with subsequent airframe damage.

All of the above could by followed by runway excursion and post-crash fire.

Anticipated Impact on Crew

In case of a gear problem, the crew bears significant stress. They will need time to fully assess the nature of the problem. Further steps could include crew visual inspection (depending on aircraft design), manual emergency landing gear extension, or flight manoeuvres designed to force the drop of the landing gear. All of these steps require significant preparation.

Several low pass approaches might be necessary to be performed in order to inspect visually the landing gear status and position by qualified technical personnel.

A landing with confirmed unlocked gear could result in emergency evacuation of the aircraft and the cabin crew will need to prepare the cabin and passengers for such an event.

For further information, see the separate article: "Landing Gear Problems: Guidance for Flight Crews"

Suggested Controller's Actions

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 gear problem, ask for the crews’ intentions when the situation permits, and establish whether the crew is able to extend the gear into locked position;
S - separate the aircraft from other traffic, 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 services and all concerned parties according to local procedures;
S - support the flight experiencing gear problems with any information requested and deemed necessary (e.g. 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.

What to Expect

If a crew has declared gear problems, the controller may anticipate:

  • Need for time to resolve the exact nature of the problem;
  • Holding pattern request for preparation and execution of manual extension;
  • The necessity of time and place to perform specific manoeuvres with the purpose of full extension;
  • One or multiple low passes for visual inspection;
  • Low speed approach;
  • Need for rescue and fire services to be on standby;
  • Runway blockage after landing;
  • Aircraft Evacuation.

What to Provide

Apart from the above mentioned, a controller should:

  • Transfer affected aircraft to another frequency, if applicable;
  • Maintain close coordination with ground emergency units - an early call could facilitate more effective deployment of resources;
  • Have direct contact with aircraft operator’s technical representative (if possible) - any result of a visual inspection should be passed to the crew without delay.
  • Be prepared to rovide a wider range of information to the crew on request.
  • DO NOT certify the down and locked position of the landing gear - visual inspection during low pass should be done by qualified personnel. If not possible, the tower controller should provide information about landing gear not extended or only partly extended to the aircraft concerned without delay.
  • Use the proper phraseology as recommended by ICAO for such events, i.e. “The landing gear appears down” and “Landing gear appears up”. Useful phraseology utilised for such events is included in UK CAP413 Radiotelephony: Section 1.9.6, which states:

"If the low pass is made for the purpose of observing the undercarriage, one of the following replies could be used to describe its condition but these examples are not exhaustive:

  • a) landing gear appears down;
    b) right (or left, or nose) wheel appears up (or down);
    c) wheels appear up;
    d) right (or left, or nose) wheel does not appear up (or down).

Defences

  • Provide timely response to crew;
  • Allow time and space for the affected aircraft;
  • Provide sufficient personnel in order to transfer affected aircraft to own frequency.

Accidents and Incidents

  • A320, Los Angeles USA, 2005 (AW): On 21 September 2005, an Airbus A320 operated by Jet Blue Airways made a successful emergency landing at Los Angeles Airport, California, with the nose wheels cocked 90 degrees to the fore-aft position after an earlier fault on gear retraction.
  • A310, Vienna Austria, 2000 (LOC HF AW): On 12 July 2000, an Airbus A310 being operated by Hapag Lloyd on a non scheduled passenger flight from Chania to Hannover declared an emergency due to fuel shortage and, after making an en route diversion to Vienna in day VMC, crash landed short of runway 34.

Related Articles

Further Reading

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