I'm with Wiley & 411A
We had the same "20 minutes = no delay" from the UK CAA for many years (
so no guessing whom the GCAA copied it from, eh?!)
Nb. Company Minimum Reserve (
CMR) = Diversion Fuel + Final Reserve (
30’ holding at 1500 ft overhead your alternate).
It’s the CMR figure which you put into the FMC’s / PERF INIT page / RESERVE field ... indeed sensible pilots (
imho) will add a few hundred kilograms to this to ensure an early ‘heads-up’ that you’re getting close to CMR and need to make a decision about staying or diverting (‘
coz it’s a bit late when you get to CMR to then start making your mind up as to what to do... as you’ll see in a minute).
Now imagine that you’re approaching DXB (
or some such multi-runway’ed airport) and are told that you can expect to hold for 24 minutes (=
6x around the hold). It’s evident that the reason for the delay is traffic flow, the airport is fully serviceable and that it has several runways available. There are a couple of scenarios to consider:
- If you look at the FMC and it predicts that you’ve got enough fuel in the tanks to hold for 28 minutes before you reach CMR – there’s therefore no problem, so carry on holding. Uhm, but what if you get to the point where you’ve been around the hold 6x, you’ve reached CMR fuel, the FMC is bleating “Insufficient fuel” and ATC say that you need to go around 2 more times.... are you really going to divert?
- Now imagine that you’ve been given a 24 minute delay and you’re FMC says that you only have enough fuel to hold for 18 minutes before you reach your CMR... would you divert then?
Imho, so long as you are reasonably assured of landing at your destination (
e.g. the weather’s not a factor, there are multiple runways, either at the destination airport or very close by) then it is perfectly reasonable to ‘commit’ to your destination and to use your Diversion Fuel to do so.
Of course some will say “
But what if the aircraft in front of you has a problem and blocks the runway to which you’re approaching to land”... A) multiple runways are available and / or close by (
Ras Al Khaimah,Sharjah, etc)... and besides, who’s to say that the same couldn’t occur to the runway you’re diverting to and / or what assurances do you have that there are no delays at your diversion airport (
in which instance you’ll probably arrive at you alternate with even less fuel than if you’d stayed in the hold and landed at your destination, right)?!
Needless to say, there comes a point when you have to make a decision to either stay or divert.
If you’ve elected to stay in the hold, go below CMR, but then decide to divert,... given that the diversion fuel is a fixed figure, the fuel that you’ve used to hold below the CMR would be the fuel available for the ‘Final Reserve’ and, therein, you will necessarily be landing with less than Final Reserve – so you must then declare a "
Mayday".... accordingly it might have been better to stay where you were, i.e. in the hold, committing to and landing at your original destination rather than to have diverted.
The need for Diversion Fuel + Final Reserve is a ‘planning’ requirement, it does not dictate what you must do with it once airborne.
All imho.
The following (
hence the edit) is cut / pasted from,
CAR / Part 4 / OPS 1 / Subpart D:
1-D-23 01 January 2008 / Appendix 1 to CAR–OPS 1.375 / In-flight fuel management:
(b) In-flight fuel management.
(1) If, as a result of an in-flight fuel check, the expected fuel remaining on arrival at the destination is less than the required alternate fuel plus final reserve fuel, the commander must take into account the traffic and the operational conditions prevailing at the destination aerodrome, along the diversion route to an alternate aerodrome and at the destination alternate aerodrome, when deciding whether to proceed to the destination aerodrome or to divert, so as to land with not less than final reserve fuel.