Are You Prepared?

Stansted’s training aid TriStar sits with its nose and starboard wheel ‘stuck’ in the grass prior to the recovery exercise in November. (All images Duncan Cubitt www.duncancubitt.com)

Tom Allett visited Stansted Airport to witness an aircraft recovery demonstration staged to mark the opening of Stansted’s ARTCC.

Stansted’s training aid TriStar sits with its nose and starboard wheel ‘stuck’ in the grass prior to the recovery exercise in November. (All images Duncan Cubitt www.duncancubitt.com)

On November 25 I travelled to Stansted, London’s so-called third airport, to see the opening of its Aircraft Recovery Training and Competence Centre (ARTCC).  Stansted is fortunate in having the all the ingredients to make such a facility work.  It already had the space available on its north side; out of sight of its everyday passenger operations.  It also has a substantial workforce and a retired and essentially intact TriStar wide-bodied airliner to act as the ‘patient’.  All that was missing was the on-site recovery equipment, but now that finishing touch has been supplied by the French-based company Deschamps.
Now, anyone who knows anything about the British climate will realise that November is not the best month to be standing outside on a windswept airfield.  However, the weather gods were smiling down on us and we were grateful that the winter sun lit up the proceedings.
The scenario was that the aircraft’s nose and starboard undercarriage wheels had left the paved surface, and got stuck in the mud, marooning the giant airliner in the process.  The Stansted recovery team was tasked with lifting the TriStar’s starboard wing with two inflatable air bags.  When the aircraft’s wheels were clear of the ground a tough mobile Tow Mat was to be slid underneath them.  A similar exercise would then be carried out on the nose gear, though it would be lifted clear of the ground by a giant crane.  When both sets of wheels were secure on their respective Tow Mats, the aircraft was ready to be towed back onto the paved area.  As the assembled group of invitees waited for the exercise to get underway, my mind wandered back to a similar scene I had witnessed several years earlier…
 

Two 40-tonne recovery cushions were inflated under the starboard wing and the wheels are lifted from the ground.

Memory Lane…

More than a decade ago, when I worked at Plymouth City Airport in the southwest of England, blustery crosswind conditions caused the scheduled flight of a DHC Dash 8-300 airliner to end in a crash landing.  As the aircraft’s port main landing gear struck the runway hard, it snapped the shear-pin which held that undercarriage leg in the down position, allowing it to gradually collapse in the manner it was designed to in such circumstances.  Its designers had realised it was better to have the undercarriage collapse than build it so strong that it would damage the integrity of the wing, and ultimately, its internal fuel tank.  Thankfully there were no injuries, no fire, and a successful evacuation was carried out efficiently.
After it was established that all the passengers and crew were safe and well, thoughts turned towards the aircraft clear-up operation.  As is the routine for such incidents, the Air Accidents Investigation Board (AAIB) was informed, and duly arrived to begin its detailed investigation.  At around the same time, the recovery operation was also getting underway.  The aircraft had suffered significant damage but was repairable.  Its starboard main gear was intact and although the nose gear had sustained some slight damage it was still supporting the aircraft.  The port wing tip had struck the ground and the port engine’s propeller blades had largely disintegrated when they struck the runway.
The first piece of a chain of Tow Mats is slipped into place before the wheels are lowered again.

Unfortunately the Dash-8 had come to rest close to the intersection of the airport’s two runways, thereby closing it to all fixed-wing aircraft movements.  The aircraft’s operator had its own engineering facilities on site, but in order to move the airliner to the hangar, it was necessary to lift the wing before the aircraft could stand upright on its undercarriage again.
A truck was dispatched from London’s Heathrow Airport containing an aircraft recovery kit, and this included a number of inflatable rubber bags.  The plan was that the bags were to be used to raise the port wing high enough so that a jack could be fitted underneath it.  With the jack in place, the wing could then be raised further, allowing a temporary repair to be made to the undercarriage, thereby enabling it to be towed back to the hangar.  With the aircraft sent on its way, the clear up operation could then be completed…
Well that was the plan, but it didn’t quite run as smoothly as had been hoped.  To be fair, travelling from Heathrow to Plymouth Airport by road is not the most pleasant of journeys under any circumstances.  In an articulated lorry, even driving non-stop in good traffic and weather conditions, it is likely to take you six to seven hours.
The crash-landing had taken place just before mid-day on a Sunday afternoon.  Now, although Plymouth is far from being the UK’s busiest airport, its business links are vital to the local economy.  Although it didn’t occur during the airport’s peak flight time, the rest of the day’s flights had to be cancelled, leaving passengers travelling on flights to or from Aberdeen, Bristol, Cork, Jersey, London, Newcastle, Newquay and Paris to be re-routed via the best means available.
The Tow Mat gives the wheels a firm footing which will allow the aircraft to be towed out.

Due to the long road journey from Heathrow and the length of the winter days, it was dark by the time the recovery team arrived at Plymouth Airport.  Like every other airport, Plymouth’s exposed location gave some cause for concern as we wondered if the wind speed would prevent us from using the inflatable bags.  Well, the weather was relatively kind that evening, but hopes of a ‘quick’ recovery were dashed when it was discovered that the wrong type of inflatable bags had been loaded at Heathrow!  To say that this was a major disappointment to everyone involved can only be described as a typical British understatement!
Nothing could be done; the truck returned to Heathrow with its unwanted load and returned with a new crew and the right equipment in the middle of the following day.  Valuable time and another day’s flying had been lost.  By the time the runways were ready to be reopened, the airport had been closed for almost 48 hours and at least 40 arrivals and departures had been affected.  It had been a very expensive episode, though thankfully only in financial terms, and was one of the longest-lasting closure periods in the airport’s commercial history.  Back to the future
A final check that everything is ready...

My mind snapped back to Stansted as the recovery exercise got underway.  In accordance with the TriStar’s technical manual, two of Deschamps’ 40-tonne Aircraft Recovery Cushions (DARC) were positioned and inflated underneath the airliner’s starboard wing.  Gradually the starboard main-wheels were lifted to a height of around 12 inches (30cm) above the grass; then the first section of its aircraft Tow Mat was placed underneath the wheels enabling them to be lowered on top of it.  A chain of Tow Mats was soon linked together and stretched back to the paved surface.  Next it was time for the nose-wheel to be hoisted up.
Again, in accordance with the aircraft manufacturer’s technical manuals, a crane lifted the nose-wheel clear of the ground, using Deschamps’ Spreader Bars (see front cover image) to avoid excess force being applied to the fuselage.  Then, with the nose-wheels suspended just about the ground, another line of Tow Mats was moved into position and the aircraft looked set for towing.  Lines were attached to the main undercarriage legs and an airport snow plough was used to haul the TriStar back on to the asphalt – job done!
Of course every recovery is different and the demo we had witnessed was only meant to give a general idea of how the equipment works, rather than an accurate assessment of all the problems that an airport’s recovery team would encounter.
With the Tow Mats in position, the tractor is ready to pull the aircraft back on to the asphalt.

Real hands-on aircraft recovery training courses for interested parties will begin at Stansted in the spring of 2010, though no firm dates have been announced yet.
Is your airport equipped to deal with recovering a disabled aircraft?
Can you afford for it not to be?