Sunday, 13 August 2006 08:38
Hey Captain Lim,
I have come to know a lot more about air travel lately. On my first flight, I was extremely relaxed during the landing because I had no idea really that it was possible to overrun the runway.
I was just wondering, how common is it for an aircraft to overrun the runway? Being a captain, I would like to know if it is hard to try and stop the aircraft in time.
Any information would be appreciated.
All planes must be able to perform to the specific requirement (e.g. stopping within a particular distance) before they are certified to be airworthy for the carriage of passengers. Similarly, all runways must be of sufficient length to meet FAA Regulations so that planes do not overrun the runway. That said, why some planes still end up on the ditch at the end of the runway? Well, landings and take offs are more scientific than what most people thought.
On departure, all planes must satisfy the balanced field length - meaning that the runway must be long enough to ensure adequate stopping distance in case the pilot decide to abort a take off due to an emergency. On arrival, pilots must refer to manuals to make sure that the runway is long enough for the landing. Nothing that affect the performance of the landing distance is left out during the calculation - the aircraft weight, surface wind, temperature, runway slope, whether icy, snow covered or wet after a rain are taken into account. On top of that, a buffer of 15 % is added to the calculated distance.
Well, if it were so, how come the Air France Airbus A340 overran the runway at Pearson International Airport in Toronto on 2nd August 2005? (Aircraft was destroyed in a post-crash fire with 43 minor injuries and no fatalities) The official inquiry will probably reveal the true causes in the distant future but it is speculated (with a disclaimer) that pilot error may be the contributing factor. The pilot overshot the touched down zone and landed 4000 feet into the 9000 feet long runway with a tail wind and wet surface.
Yes, possibilities of contributory causes abound. Besides human errors - pilot*s temptation in a hurry to land after a long flight, unstabilized approach, ineffective application of spoilers after touch down and others like thunderstorms in the vicinity, wet runway, tailwind also play a role in the accident. Whatever the reasons, a captain makes the final decision to abort the landing and go around if he thinks it unsafe to proceed. It is hard to say why it was not done without the full inquiry report.
So how common is it for an aircraft to overrun the runway? Well, it is very rare. If it happens, is it hard to stop the aircraft in time? In the first place, a captain, through his rigorous training, should never allow it to happen. If everything is against you - the runway is short, a strong tail wind, ground spoilers not working, runway is wet or icy - then you have to pray very hard! However, if the runway is long with a designated stopway, then it is possible to stop the aircraft in time. So it all depends on the environmental conditions and the length of the runway in use.
As regards to the Air France A340 accident at Toronto, the Air Line Pilots Association (ALPA) released a statement two days after the event that the airport authorities failed to construct an adequate stopway zone or install an arrester gear at the end of Runway 24L where the accident happened.