Haroon, in virtually all situations, particularly the one which you describe, then the safest option should be taken, I remain with option (B). If you judge that you can do otherwise then you have to be prepared to justify your decision – possibly in the worst of circumstances, an accident which was not foreseeable or necessarily of your making. You would still have to justify why you were flying the chosen option where the safer alternative may not have resulted in the accident factors coming together. Consider a hindsight view and turn it into foresight.
Re your quote from Checkboard; I don’t believe that this view necessarily agrees with the assumptions held by the certification agencies.
Currently I am unable to locate any regulatory material to support this. However, the following is taken from a 2002 certification conference:
“
There is no readily identifiable underlying technical explanation of the operational landing distance factors, which have existed for some time” and “
The factors have now become ‘accepted’ as providing a satisfactory safety record. However, subsequent research into the industry’s concerns about overruns reported:-
For dry runway the current operational factor of 1.67 for both Destination and Alternate airports appears to be reasonable
For wet runways, without reverse thrust:
1.92 for Destination airport appears to be low
1.67 for Alternate airport appears to be really low
For wet runways, with reverse thrust:
1.92 for Destination airport appears to be marginal
1.67 for Alternate airport appears to be low
Flight Working Paper 730 and Transport Canada Aircraft Certification Flight Test Division Discussion Paper No. 22
From the Loughborough University Report “A New Aircraft Overrun Database 1980-1998 based on data from “English-speaking world”:
A high proportion of overruns involve near or over maximum weights
Three times as many overruns in landings than aborted takeoffs
Wet runways, contaminated runways and tailwinds are factors in many overruns, particularly landing long and fast.
The overrun accident rate in recent years might suggest that the industry is operating too close to limiting conditions, particularly with respect to human judgment; thus this links with
Intruder’s comments (#14).
Once we entertain the thought that we might be able to land overweight, then we suffer bias – a tendency to find supporting information. The example questions given seek to justify the factor; none of which individually or collectively are sufficient or correct.
The factor (in UK CAA terms) is a landing distance
safety-factor. It identifies with that undefined margin that we should seek to provide in all of our flying.
Instead of thinking ‘can we land’, we must question our assumptions and consider ‘should we be landing’ in these conditions.