Rules of Thumb
A few handy rules of thumb for flying the 737-3/4/500.
Speed, Height, Distance conversion
Level flight deceleration allow 10kts/nm & 1kt/sec (deceleration is faster at lower weights)
Descending deceleration allow 5kts/nm & 0.5kt/sec
Idle descent allow 3nm/1000'
Approach Profile Planning
Aim for 250kts, 10,000ft by 30nm out
Aim for 210kts, On ILS at 12nm
Cruise N1
N1 = (2 x Alt/1000) + 10 eg at FL350 = 70+10 = 80% N1
or
FF = (IAS*10)/2 -200 eg 250kts = 2500/2 -200 = 1050 kg/hr/engine
N1's & Pitch Attitudes
Phase of flight
%N1
Attitude (deg nose up)
Level Flight:
250kts
65
4
210kts
60
6
Flap 1, 190kts
60
6
Flap 5, 180kts
62 7
Gear down, flap 15, 150kts
70
8
Gear down, & on glideslope:
Flap 15, 150kts
52
4.5
Flap 25, 140kts
52
4
Flap 30, Vref + 5
55
2.5
Flap 40, Vref + 5
62
1
All the above based on a gross weight of 47.5, N1 may vary by 5% and attitude by 2° at other weights.
Add 2% N1 in turns.
For single engine add 15% N1 + 5% N1 in turns.
Climb Speeds
If ECON info not available, use 250KIAS until 10,000ft then 280KIAS/M0.74 thereafter.
Best Angle = V2 + 80
Best Rate = V2 + 120
Kinetic Heating
Is approximately 1°/10kts IAS
Fuel Burn Vs Level
The 737 burns approx 30kg/min. Hence subtract (30kg x reduced trip time in mins) from the trip fuel at the proposed level. If this figure is less than the trip fuel for the planned flight level, the lower level is justified.
Trip Fuel Reduction
TFR = Weight reduction x Flight time in hrs x 3.5%
eg 60pax = 4200kg x 1hr x 3.5% = 147kg lower trip fuel
All taken from
www.b737.org.uk/rulesofthumb.htm if anyone has any more let me know and I will add them to the list.
S & L