NGs -700/-800 N1 on final approach

[Becker Junior]

Is there any usable "rule" between acft weight and N1 value during final approach on -700 and -800?

[Ashling]

Gross Weight in KG + 2% is a good starting point.

[AERO_STUDENT]

As a ballpark figure (700)...if the PM's CDU is showing Gross Weight....try that as an N1 setting. Won't be too far away. That's for Flap 30 VREF. For a Flap 40 Approach, roughly add 5%N1.

[flyby797]

a another way is using the Vref you selected: you read for example on the PFD 30/134. A approximate and good value for the N1 is : 30+(2x13) that is 56%. And it works

[Kit d'Rection KG]

I must admit I'm amazed that people fly like this - I never could, and still can't!

I just adjust the thrust in the way I would alter power if flying a smaller aircraft, and it works - for me, at least.


On a more serious note, if you are going to do this mathematical stuff, you'll need to consider wind... Do any of you factor that in at the 'What N1 do I set to start with?'' stage?

[RAT 5]

For an 800 NG I use a simple start point datum N1% and then make small adjustments accordingly. The LDW doesn't seem to make so much a difference as increased headwind and thus a faster Vfly = higher N1%; conversly a tailwind = lower N1%. I find the weight has to change significantly from a ball park normal 62.0 to make a difference.

Try 53% F30 & 64% F40 as a datum. ( 3 & 3 or 4 & 4)I'm a simpleton and they are easy to remember and often not far out. For 15-20kts wind additive it'll be an extra 5% max. I suppose the GW is about right for F40 & -10% for F30, if your mind works that way. What is also useful is circuit power for level flight. 6 % 60% works for a great many modern jets. You mentioned small a/c thrust/power management techniques; believe me, for a jet it is far easier and quicker to know a power/attitude datum for circuit configurations; start there and make small adjustments. Searching for the correct setting will occupy too much concentration and leave too little brain power for controlling all the other parameters; even worse when something goes wrong and you are still trying to stabilse the a/c. On under slung engines ever changing thrust leads to ever changing pitch trim, and that is a headache best avoided.

[5150]

I'm with Kit on this one!

Talk about over-complicating something. . . !

[Fell_Off_The_Jetway_Again]

Knowing appropriate pitch power combinations seems essential to my mind if one wishes to maximise one's capacity to perform tasks beyond directly flying the aeroplane.

Returning from a long haul night flight, dirty weather, turbulence, various non-normal situations such as unreliable airspeed, training low-hours or new on type pilots, hectic simulator details: these all seem to justify a working knowledge of pitch power settings. It just makes life easier.

I must admit that as a reasonably experienced first officer, I did used to wonder what all the fuss was about - just fly the plane, use your basic flying skills and rapid scan to stabilise the aircraft smoothly and rapidly in each phase of flight.

Now, however, as I've matured into a reasonably inexperienced skipper, I have learnt the full value of knowing pitch/power settings: flying the plane as a task in itself seems to have become secondary to all the other myriad thoughts I now seems to have, and I'm not too proud to admit that I'll take all the help that I can get!

As I said, if I can set a ballpark pitch power setting for any phase of manual flight I'm in, it simply frees up some capacity to do something else or get further ahead in future management tasks which I know will pop up later. :)

Out of interest, are 5150 and Kit flying LHS or RHS?

[Kit d'Rection KG]

For me, both. I do think this is mostly a matter opf personal taste. I fly about seven or eight types, none of them very often, and from both seats. If using ball park figures works for you, fine. The only ones I remember for the 737 are 6 and 60 - the 'get you out of trouble' ones!

[vwreggie]

Trained as lhs and presently flying rhs classics and 800. on selecting final flap we generally have the PF with the init ref page up to confirm that the final flap selected is the one that was briefed on. This shows you the present landing weight.

I tie the selection of landing flap/final flap to a check that the thrust levers are at least 45-50% as the speed bleed will catch you out before spool up.

On a 800 if you are looking for ball park last look N1% thrusts then WT-3% for a F30 landing and WT+3% for a F40.

Classic then F30 60% and F40 64%

[xetroV]

I fly too many 737 variants (both classics and NG's) at too many grossweights to remember all these rules of thumb. Just this week I have seen Vrefs as low as 120 kts and as high as 170 kts on two subsequent legs on the same day.

For me, 55% N1 usually works fine as an initial setting (60% for flaps 40, 65% for single engine/flaps 15). Of course it's a little higher if you're heavy and a little lower if you're light, but I like round numbers, and I rather start with a pretty rough but workable estimate than with an accurate "guesstimate" for the wrong subtype! And anyway, no matter how good you estimate the target N1, it still remains just that: a target value.