B777 RECMD Altitude and Step At

[extricate]

Hi there,

Anyone has any idea why oftentimes in CRZ page, RECMD alt recommends, say FL 350 and LSK 1R shows STEP TO FL350 and below it, it shows AT XXXXz and XXXnm?

Can't we just climb to FL350 now since it's RECMD? Why is there a specific point?

Thanks

[birdspeed]

Can’t remember what parameters the RECMD looks at. But I just ignore it, as everytime you glance at it shows a different level. It jumps around too much.

[fox niner]

The 777 is a great airplane. However, I get really ANNOYED by the nuisance [ ] VNAV STEP CLIMB eicas message. When and how did this ever get introduced into the electronic checklist? I flew the 777 from 2005-2011, and back then this nuisance didn't exist. I got confronted with it last year when I returned to this A/C type. The airplane doesn't understand that no matter what I would try to do, ATC does not always make a step climb possible.
Does anyone know what Boeing is trying to achieve by introducing this and similar other nuisance NNCL procedures, such as [ ] INSUFFICIENT FUEL. ?
I usually see this fuel eicas message at the gate, just before pushback. Fuelling has been finished, the block fuel is on board, and the stupid airplane has decided that somehow I have "insufficient fuel". No I don't, block fuel is on board and the winds are not yet entered in the FMC. So don't bother me with these nuisance NNCL procedures at critical moments mr. Boeing. Thanks.

When did these get introduced? And Why?

[wiggy]

Story I heard was Boeing introduced the idiot messages such as “Step...” to cater for the lowest lowest common denominator when it came to operators....

May be the likes of tdracer can confirm/deny, but I’d agree that to anyone with a modicum of sense these messages are a real PITA..

[Sidestick_n_Rudder]

Yup, that's definitely the most annoying EICAS message ever… The associated checklist is stupid too. I could understand if it just said "consider step climb", or some such, instead of two pages with several yes/no options

Having said that, it seems to have stopped popping up on our 787's since October, or so… Has Boeing finally come to its senses and changed the software?

[Roo]

..
Anyone has any idea why oftentimes in CRZ page, RECMD alt recommends, say FL 350 and LSK 1R shows STEP TO FL350 and below it, it shows AT XXXXz and XXXnm?

Can't we just climb to FL350 now since it's RECMD? Why is there a specific point?
You can climb now, but the STEP TO point is more accurate because it takes more into account.

This is for the 78. I expect 777 is much the same.

RECMD only considers current position and out to 250 to 500nm ahead, depending on step size. It does not consider fuel for climb to the new altitude. It considers levels down to 9,000' below and up to MAX. The trigger for a change is low and may only require a gain of a few kg. Therefore RECMD can hunt around.

STEP TO only offers Climbs (because Boeing thought a STEP TO descent would be silly and ignored), accounts for Climb (and Descent to original level at end of cruise) and considers the winds out beyond 500nm.

So climb based on STEP TO rather than RECMD is more efficient. As STEP TO will never offer a descent, you need to consider RECMD when a consistently lower RECMD level is presented. This could occur when there are markedly better winds at lower levels.

[fox niner]

Story I heard was Boeing introduced the idiot messages such as “Step...” to cater for the lowest lowest common denominator when it came to operators....

Thanks wiggy, I heard that rumor as well. I was hoping for a different reason. Now I have to deal with the problem of sharing the skies with “lowest common denominators”. I dont like that either.

[sleeve of wizard]

To further expand on what Roo has said.
RECMD is constantly updated, and calculates the Optimum FL at your current position with a range of 250nm (NAT HLA / 1000ft), 333nm (RVSM/ 2000ft) or 500nm (ICAO/4000ft)

[ElZilcho]

The VNAV Step EICAS was always infuriating. Used to avoid it by manually putting steps in the Legs page further downtrack before it flashed at us.

A good way to examine STEP TO and RECMD in flight is to change the Cost Index. A large increase in CI can greatly reduce your RECMD Altitude but the STEP TO will never tell you to descend. Another example is updating the Winds/Temps. A noticeable change from what was entered pre-flight could change the RECMD altitude but once again, you wont get a Step-Descent.

[EDDT]

To get rid of nuisance "VNAV Step Climb" Eicas messages, you can enter "0" in the field step size.

One question: is it still true that winds are updated at 4,10,16,22 hrs UTC ?

[punkalouver]

To get rid of nuisance "VNAV Step Climb" Eicas messages, you can enter "0" in the field step size.


Normally this is done as soon as you reach the S/C on the ND. I believe that the EICAS Message appears after a certain time period after the S/C when the aircraft has not actually initiated a climb.