(As mentioned by Bhoy elsewhere) the Britannia 757 carrying the Celtic squad to and from Kaunas in Lithuania was forced to abort it’s takeoff in the early hours after the pitot tube feeding the airspeed indicator became blocked, rendering the indicator useless.
In the Evening Times report the journalist says the crew performed an “emergency stop”. I’m just wondering if this is the appropriate terminology for such a procedure ? Or indeed does the 2nd officer have to wait until the captain taps the dashboard with a clip-board before performing one ? (lol) 😀
A replacement plane has been despatched and is due at GLA at 1710 this evening (Thurs) I might head down for a picture or two. Probably won’t be the all white 757 though.
By: Moondance - 2nd August 2003 at 09:53
Steve – the two accidents to which you probably refer are the Birgenair B757 (blocked pitot, or should that be “peto”, don’t you just love journos?) and the AeroPeru B757 (blocked static ports), both in 1996. Read the reports on http://aviation-safety.net/index.shtml Having tried the the AeroPeru scenario on the simulator, it is a very alarming and confusing situation to find yourself in – read the Birgenair report and you see they had almost simultaneous stall and overspeed warnings. Having worked out what the problem was, we managed to fly the sim using the radio altimeter (which is only effective within 2500ft of the ground) and groundspeed readout from the IRS (Inertial Reference Systems).
By: wysiwyg - 1st August 2003 at 10:55
The term for this is an RTO (rejected take off). The way it is performed varies from company to company but I’ll explain how we would do it.
We tend to fly in turns, one pilot flies there and the other one flies back so we wouldn’t refer to ourselves as Captain and First Officer but Pilot Flying (PF) or Pilot Non Flying(PNF). We are both trained and licensed to exactly the same level (the First Officer is just waiting for the other guy to die so he can get the pay cheque!) so if it was the First Officers sector he would be PF and the Captain would be PNF. Clear so far?
On my company’s 757s we only have a steering tiller on the left side of the cockpit so the Captain assumes PF during the taxi out before take off and after landing for the taxi in. If it is his sector he would also remain PF for the whole flight. If it is the FO’s sector he would take over as PF before the start of the take off roll and reume PNF at the end of the landing roll.
In this scenario imagine we are just about to start the take off roll. PF (in my company) would ask PNF to set 1.2 EPR on the engines which gives us a chance to get them stable and check parameters before comitting to the take off. PNF, when happy with the indications would call ‘stabilised’ and the PF would then engage the autothrottle which will advance the thrust levers to the preselected take off thrust setting. The PNF pays particular attention to the engine parameters as well as monitoring the airspeed indicators (all 5 of them – 2 main ASI’s, 1 standby ASI and 2 speedtapes on the attitude indicator) for increasing airspeed. His next call would be ’80 knots’ on passing that speed. This is a dead mans call for which if he does not here the response ‘check’ he can assume the PF has become incapacitatated and should assume control, rejecting the take off. In this scenario the lack of airspeed build up would have nbeen noticed by the PNF and a ‘STOP’ call made. The aircraft would be brought to a halt by closing the thrust levers, manually raising the speedbrakes, applying maximum reverse thrust (in accordance with maintaining directional control) but using manual wheel braking as the autobraking system would not yet have armed from such a low speed reject.
The next actions would be to inform the tower, vacate the runway and consult the brake cooling schedules to verify that the brakes are ok for taxiing back to stand (which they will be from such a low speed reject).
Hope this helps
wys
By: steve rowell - 31st July 2003 at 23:56
I seem to recall a couple of accidents where the blocked pitot tube was to blame for the pilot stalling the aircraft because of a false speed indication
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July 31, 2003 at 2:14 pm