Estimated IAF Fuels

CHAPTER TWO

INTERMEDIATE FLIGHT PREPARATION WORKBOOK

NOTES

1. A 6-minute gate is the GS in knots divided by 10 (since six minutes is

a tenth of an hour), and a 5-minute gate is the GS in miles per minute

multiplied by 10, then divided by 2.

2. Use aircraft clock (FT mode) for ETAs vice the elapsed time mode.

Estimated IAF Fuels

Estimated fuel at the IAF is given during the WL call and after each GS check. Several

techniques for fuel computation may be used. Four will be explained in the following

discussion. The following examples use the information below:

DISTANCE AND ETE1:

NEXT PT.

IAF/NEXT PT.

IAF

Pt. #1

140/770

0+20/1+50

Pt. #2

N/A/ 630

N/A /1+30

You mark-on-top of Pt. #1 at 40+00 with 4100 lbs of fuel. Enroute to Pt. #2 you complete a GS

check: You are traveling 420 KTS (7 NM/min). When you "freeze" the fuel quantity and fuel

flow, you have: time (44+00); fuel now (4040 lbs); fuel flow (1200 lbs/hr); distance to Pt. #2

(112 NM). Compute IAF fuel for wings level after Pt. #1 and IAF fuel after GS check.

GS Check:

112 NM 7 NM/min = 16 min to Pt. #2

16 min (to Pt. #2) + 90 min (Pt. #2 to IAF) = 106 min (to IAF)

Pounds Per Minute Method: Divide fuel flow by 60 to determine pounds per minute.

Multiply pounds per minute by minutes remaining to IAF.

1200 lbs/hour 60 min/hour = 20 lbs/min

Wings Level: 106 min x 20.0 lbs/min = 2120 lbs fuel burned to IAF

4040 lbs - 2120 lbs = 1920 lbs at IAF

Adjusted for preflight winds

2-12

T-1A FLIGHT PROFILES