PPRuNe Forums - View Single Post - Calling V1 early
View Single Post
Old 29th Jan 2006, 10:20
  #6 (permalink)  
Centaurus
 
Join Date: Jun 2000
Location: Australia
Posts: 4,186
Likes: 0
Received 6 Likes on 4 Posts
I have read too many accident reports to be convinced there is no problem with an abort on a balanced field length from a engine failure close to V1 even if the crew performs perfectly in all respects.

The veracity of these accident reports over the years is further confirmed from what I observed on countless occasions during simulator training. Having watched experienced and inexperienced pilots occasionally stuff up an abort in the simulator due to factors such as not immediately being aware that an engine has indeed failed. Or that noise and a heavy vibration accompanied by a swerve might mean a tyre and not an engine has failed. Or an unusual engine instrument indication is brought to the pilot's notice at a critical time by the PNF in the take off run.

There is a pragmatic approach to the question of abort speed and there is the official company approach based upon the manufacturer's figures. Rightly or wrongly I have always quietly planned on continuing the take off from 15 knots below the published and bugged V1 - unless the event is catastrophic, in which case all bets are off. Others may vehemently disagree and I have no problem with that.

Forget the lower screen height - when the chips are down the deadly risk is the over-run from a botched abort at high speed nearing V1. My simulator observations of aborts gone wrong over the years have biased my thoughts toward the V1 minus 15 knots policy I prefer. Of course I would not insist other pilots do what I do. It is just a private conviction that I would act on. The chances of an abort going deadly wrong are a thousand times higher than hitting an obstacle in the first or second segment in IMC because of a low screen height coupled with a real net flight path climb out.

Sitting in down the back cattle class I would be terrified if late in the take off run I heard the engines suddenly cut a minute into the take off run and the sound of screaming tyres, brakes, and reverse thrust - knowing from memory the chances of a botched up abort were high. I would be less terrified if an engine failed near V1 and I realised the pilot was continuing the take off run.

As far as the V speed calls by the PNF, I suggest concentration on my own ASI reading - not the V speed calls by the PNF. Again in the simulator I have seen too many incorrect V speed calls by the PNF to act blindly on his call, rather than my own ASI backed up by the planned ground speed display. The PNF call is a back up only - not the action call. The V speed word (not command) "Rotate" can be a powerful incentive to pull back on the stick simply because of the word itself.

It is a not uncommon sight in the simulator for the PF to momentarily disbelieve his own ASI and instead be startled enough to rotate at the call of "Rotate".

Last edited by Centaurus; 29th Jan 2006 at 10:35.
Centaurus is offline