Deriving NBAA alternate fuel requirements:
Requirement
|
Fuel Burn
|
Distance
|
Speed
|
Required Fuel |
| Climb to 5000' |
|
5 |
|
40
|
| Hold 5 Minutes |
627 pph |
|
|
52 |
| Climb to 15,000' |
|
17 |
|
80 |
| Proceed to Alternate (100 NM) |
698 pph
|
52 |
251 KTAS |
145 |
| Proceed to Alternate (200 NM) |
698 pph
|
152 |
251 KTAS |
423 |
| Descend at 3000 FPM |
|
26
|
|
36 |
| Fly IAP (5 min) |
754 pph |
|
|
63 |
| Land with 45 minutes of fuel (based on cruise at 15,000' fuel flow) |
698 pph |
|
|
524 |
| TOTAL 100 NM |
|
|
|
940 |
| TOTAL 200 NM |
|
|
|
1218 |
Red numbers are from manual, black numbers are derived.
Math not yet checked by second party.
Comments (1)
Steve Brecher said
at 5:09 pm on Nov 27, 2009
Implied rule of thumb: 800 lb plus 3 lb per mile to alternate beyond 50 mi. The more precise version: 795 lb plus 2.78 lb per mile to alternate beyond 48. The rough rule, being more conservative, would tend to cancel some of the optimism in the precise rule, i.e., that the route to the alternate, including the missed approach, is direct.
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