ICAO Step climb

[Stephane LI]

Hi, I've noticed that the FMC is calculating a 4000ft step climb for ICAO. Nowadays, most part of the world are RVSM. Shouldn't it be a 2000ft step climb instead of 4000ft when choosing ICAO in the VNAV page, like in the B777 ? I don't know about the real 747, if a real pilot can confirm that in the latest FMS version, the ICAO step climb is coded 2000ft ?

Stephane

[Hardy Heinlin]

Hi, I think the 744 FMC still doesn't allow the entry "RVSM"; only "ICAO" or a value in thousands of feet.

Here's a related thread from 2012:

http://aerowinx.com/forum/topic.php?id=1157


Cheers,

|-|ardy

[cavaricooper]

It does take 2000, or even better yet 0 and 340S in the LEGS  page at the dispatch calculated optimal step point

[IefCooreman]

Shouldn't it be a 2000ft step climb instead of 4000ft when choosing ICAO in the VNAV page, like in the B777 ?

Is it like that on a 777? (I honestly don't know, would have to check...)

It does sound like a rather strange request to me. ICAO is ICAO, RVSM is ICAO with special equipment requirements. If that equipment fails, you are not allowed to fly in RVSM airspace (although ATC might still allow you but it gives them more work, so in dense airspace you still might have to get out). I agree the use of the ICAO step climb option has become somewhat obsolete in many airspaces, but only because it's RVSM standards that are being used. It's very important to keep the distinction between both.

Cheerzzzz

[Michel Vandaele]

According my real life pilots info, the 4000 ft ICAO step is still in their cdu.  
But nowadays they use more the S/C foreseen in their OFP and are programming them in the legs pages. In the ICAO step climb box they just put " 0 " then, so they don't see false S/C signs in the N/D . It seems the S/C in the FMC are only calculated in function of the actual weight and it don't take care of the winds, which the OFP of course do.

B. Rgds
Michel

[Stephane LI]

Okay, my bad !  :mrgreen:  I've checked in the FCOM, and in the 777 they have the RVSM and ICAO options for step climb :

STEP SIZE
Displays the climb altitude increment used for planning the optimum climb
profile.
Default value is: RVSM, ICAO, or 0 as selected in AMI.
Valid entries are:  
• "0" to inhibit predicted step climbs, or
• altitudes from 1000 to 9900 in 100 foot increments, or
• "I" for ICAO, or
• "R" for RVSM
In-flight entries are inhibited. In-flight step size changes are made on the CRZ
page.
For a non-zero entry, performance predictions are based on step climbs at
optimum points. For a zero entry, performance predictions are based on a constant
CRZ ALT.

So, I will manually enter 2000 for an RVSM step climb in the B744  :lol:

Stephane