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Contents Speed,
Height,
Distance conversion Approach
Profile
Planning Cruise N1 N1's & Pitch Attitudes Climb Speeds Kinetic Heating Driftdown Fuel Consumption Fo rmulae: Optimum FL Step Search th is website:
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All of the information, photographs & schematics from this website and much more is now available in a 370 page printed book or EPUB available here . *** Updated 24 Feb 2013 ***
&
wind/altitude tra de Trip Fuel Reduc tion Anti Ice Non-Normal Configurations
Speed, He ight, 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 Ph aseo ff lig h t
%N1
Att it u d e(d e g nose up)
Lev el Flight: 250kts
65
4
210kts
60
6
Flap 1, 190kts
60
6
Flap 5, 180kts
62
7
Geardown,flap15,150kts
70
8
Flap 15, 150kts
52
4.5
Flap 25, 140kts
52
4
Gear down, & on glideslope:
Flap 30, Vref 5 + Flap 40, Vref 5+
55 62
2.5 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 Increases TAT by approximately 1°/10kts IAS
Driftdown
Driftdown speed and level off altitude are for the terrain critical case; if terrain is not critical you may accelerate to Long Range Cruise (LRC), this will cost approximately 3000ft. Otherwise slowly accelerate to LRC at the level off altitude as weight reduces with fuel burn. If anti ice is re quired, the altitude penalties are severe. See table below for figures (QRH PI.13.7).
Alti tude penalty for engine bleed requirements 737-300 737-700 Te r r ain cr it ical LRC Te r r ain cr itical LRC -1500ft -4000ft -5600ft -5900ft -4800ft -7600ft -12500ft -13000ft
Ble e d r e q u ir e me n t s EngAnti-iceON Eng&WingAnti-iceON
Fuel Consumption Formulae Optimum FL (FPPM p2.1.1)
2000ft above
Fuel Mileage Penalty % 737-300 M0 .74 737- 700 M0 .78 1 2
Optimum 2000ft below 4000ft below 8000ft below
2 4 11
2 5 14
20
24
Altitude away from optimum
0
12000ft below
Step climb & wind/altitude trade
Step climb under consideration FL290 FL310 FL330 FL370
F Þ F Þ F Þ F Þ
L330 L350 L370 L410
0
(FPPM p3.2.16)
Break even wind
Break even wind
737-300 M0.74 <34Kts <25Kts <12Kts N/A
737-700 M0.78 <75Kts <69Kts <55Kts 24Kts <
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 = Weight reduction x Flight time in hrs x 3.5% Eg: 10 pax less over a 2hr flight = 1000kg x 2 x 3.5% = 70kg lower trip fuel.
Landing Flaps Flap 30 uses 25kgs less fuel than flap 40 from 1500 ft to touchdown.
Anti Ice Engine Anti-ice burns 90 kg per ho ur. Engine + Wing Anti -ice burns 250 kg per h our.
Non-Norm al Configurations Compared to 2 Engine LRC at Optimum Altitude for any given weight: Engine Out LRC burns 21% more fuel. Engine Out LRC increases Time Interval by 13%. Depressurised LRC (2 Engines@10,000') burns 49% more fuel. Depressurised LRC increases Time Interval by 20%. Gear Down burns 89% more fuel! Gear Down increases Time Interval by 29%. Hint. you can check the Depressurised figures quoted above by page and compare the fuel remaining at your destination.
This site has had
entering 10,000' as a "step altitude" in the CRZ
visitors to date.
