Primary Engine Parameter/Manual Thrust Approach Airbus with Rolls Royce Engines

[knarfo]

Hello guys,

even though Airbus recommends to use Autothrust with manual flight, some operators still practise manual+flight manual thrust. We recently had a discussion in our airline, whether to use EPR or N1 as the primary thrust indication to be used on Rolls Royce engines for setting the proper thrust on final approach(on Rolls Royce, EPR ist the primary parameter and used for T/O calculation). In our airline currently N1 is used for thrust control on final approach. Any comments on that? What do you guys use on "EPR-engines", N1 or EPR?

Thanks for your expertise!

[Tu.114]

F70/100 (Tay 620-15 or 650-15): EPR is the primary figure for setting thrust, as unlike N1, this figure shows exactly what the engine puts out. N1 is of informational value only.

[PilotJames]

I just use N1

90% Climb
83% Cruise
53% Approach

My operator uses both CFM(N1) and IAE(EPR) engines. I use N1 for both but there is no rule that you have to use one or the other.

[Amadis of Gaul]

I'd say use whatever works best for you. In my own personal, not especially humble opinion, looking at engine displays during approaches is not the best of habits anyway. Look outside, monitor your airspeed/vector, and keep the thrust wherever it needs to be to keep everything kosher, whether it's x.xx EPR or xx% N1 is not that important.

[FlightDetent]

On IAE I do same as Amadis. My instrument scan towards N1 without TLA indicators is too slow for comfort, and I am obviously undertrained to use EPRs meaningfully during approach.

[Check Airman]

My box of pitch and power settings is all referenced to N1. I fly an all IAE fleet. I only use the EPR gauge to initially position the thrust levers- I know 50% N1 is ~1.05-1.1 EPR.

After that, the speed tape is my primary power indication.

Also interesting to note that the unreliable airspeed tables reference N1 and not EPR. My guess is that a dramatically incorrect speed indication will affect EPR- which begs the question, why bother with EPR as a primary indication in the first place?

[ACMS]

N1 basically all the time, ground and Air during manual thrust. ( A330 RR )

[EDDT]

I met a Captain setting thrust during approach by fuel flow. (Airbus 320 family)

How come your operator opposes recommendations stated by the manufacturer, who should know better ?

[ACMS]

Who me?

Unreliable airspeed checklist mentions N1
Turbulence penetration speed mentions N1

Easier numbers to remember and it's also not subject to error like EPR in icing for eg

[Capn Bloggs]

looking at engine displays during approaches is not the best of habits anyway. Look outside, monitor your airspeed/vector, and keep the thrust wherever it needs to be to keep everything kosher, whether it's x.xx EPR or xx% N1 is not that important.

I thought I'd read it all on the TCAS RA thread, but this one takes the daily cake. Ever heard of "power plus attitude equals performance"?

F70/100 (Tay 620-15 or 650-15): EPR is the primary figure for setting thrust, as unlike N1, this figure shows exactly what the engine puts out. N1 is of informational value only.

As pointed out by ACMS and as has been attested-to in the prang into the river, the EPR does not necessarily tell you what thrust is being put out. The fan on the front delivers the vast majority of the thrust and is a far more reliable thrust indication than EPR. You would be well-advised to read the report into Air Florida 90 to see how misleading EPR can be.

I use N2 on my non-airbii small Rollers. Fastest reaction of all the parameters (let's face it, N1 and especially EPR just follow along behind eventually) so I can spend more time looking outside or at the GS and VSI...

[Derfred]

I'm not sure about that Bloggs.

Actually "airspeed plus attitude equals performance"

It's just that you usually need power to maintain the airspeed. A reference power figure in your head can certainly help, but in a changing wind on approach, your airspeed is your primary concern. You set whatever power you need to maintain that airspeed.

The time to revert to "power plus attitude" is with unreliable airspeed, or certain other non-normal manoeuvres.

One certainly should be able to fly an accurate approach without scanning power settings.

[Capn Bloggs]

Derfred, this is basic IF, even if it is bouncing around on final. 83% not working, then change it, get back to the speed you want, then set something else eg 86% (N2, of course ). Sure if you get smacked in the face by a gust pull the power right off, but when you're past that, reset the power you worked out before. "Blindly" just putting the throttles "towards the front or towards the back" to control the speed won't work as well at all.

[ACMS]

Bloggsy is 100% correct yet again

I seem to recall a heated debate a year ago on a similar subject.

If you fly a big Jet then to start with you do it by the numbers they teach you in the Sim to make it easier, later on after a while you just NIKE it, even later on you learn to NIKE it AND know the numbers. For those special occasions when the poo hits the fan ( Not the N1 Fan )

[Amadis of Gaul]

Originally Posted by ACMS

Bloggsy is 100% correct yet again

I seem to recall a heated debate a year ago on a similar subject.

If you fly a big Jet then to start with you do it by the numbers they teach you in the Sim to make it easier, later on after a while you just NIKE it, even later on you learn to NIKE it AND know the numbers. For those special occasions when the poo hits the fan ( Not the N1 Fan )

In this country we use the term "fiddle" rather than "nike". Some people use the term "tweak".

[Amadis of Gaul]

Originally Posted by Derfred

One certainly should be able to fly an accurate approach without scanning power settings.

Yeah, I didn't think what I said was really all that revolutionary. Then again, maybe I'm a bit too big a believer in TLAR, TFAR, and TSAR concepts.

[Romasik]

Over 23.000 hours on different types, including 4 engine 747, I only look at engine parameters to make sure they are about the same on all engines. Except initial power set in case of unreliable airspeed. Then it's the same story - set power whatever you need to maintain the speed and change the speed trend. I don't know what is practical use of knowing the numbers.
And I love to fly manually and use manual thrust.
I also cannot recall my crew mates mentioning numbers and freguently looking at engine parameters.
Regarding unreliable airspeed. Pretty much the same technic. I mean on my present Airbus with BUSS. Just keep the speed in the green. With the same thrust control habbits. Have no idea what is EPA or N1 in the process. Once again - except initial pitch/attitude set up. But it in turn happens only for initial level off until you figure out what's going on.
Just add or reduce power as much as you need. Regardless of numbers on displays. Easy life

[stilton]

Exactly, whatever it takes is what you use, pretty simple.

[Derfred]

Fascinating.

I monitor ASI.

Bloggsy monitors N2, GS and VSI.

And both appear to work ok.