Climb gradient requirement on SID
 

Some SIDs mention a specific climb gradient requirement on the chart. for example, an RNAV SID mentioning " this SID requires 7% climb gradient". How would a pilot ascertain that climb requirement is going to be met? I am flying A320.

Thanks in advance

Your Groundspeed x 5 = Rate of Climb in ft/min

For a 7 % gradient requirement, multiply your groundspeed in knots by 7 to obtain the necessary climb rate in ft/min.

AFAIK, there is no requirement for airplane mfgrs to publish climb gradient performance. I have been unable to find it for the 744...

At, for example, 200 kts, a climb gradient of 7% is just under 2500 fpm.

No, that's not correct.

200 kts = 20 253 feet / minute
7% of 20253 = 1418 ft/minute
My rule of thumb where you multiply the required climb gradient in % by the GS in kts to obtain the required climb rate in ft/min is very close and good enough.

So, if the SID reads "this SID requires 7% climb gradient until passing 4000 ft" it comes down to a little experience. An A320 at MTOW will have a typical GS during initial climb of about 165-170 kts (no headwind). Thus a climb rate of around 1200 ft/min (170x7) is needed. Even a new pilot on A320 knows that this will easily be achieved on two engines. In case of doubt when in IMC or by night, you can consider delaying the acceleration and flap retraction until out of the restricting altitude. Make sure you have a good engine out strategy/routing if the climb gradient was necessary because of obstacles.

Cheers!

IFLY - as an 'airline pilot' you need to talk to your company Performance dept. If your a/c cannot achieve the required gradient they must produce an alternative, eg OEI SID. Actual gradients should never bother you as a driver.

Of course, if you are somewhere the company has not analysed, more work is required.

Anyone else concerned a pilot flying an A320 is only just learning about this now?

**Edit. On further thought, at least this individual realising he/she did not know the answer sought help. Better than some out there!

If you look at all the questions about the 320 http://www.pprune.org/search.php?searchid=1190277 one must assume an extremely limited conversion course:confused:

Worrying, really!

There are no bad questions!
 

The only stupid questions are the ones that are not asked. (as Water Wings seems to have realised)
May I suggest to stop making fun of/criticising fellow aviators asking question, even if you think that the answer should be obvious!

sb - the point you are missing is that some 'airline pilots' appear to be operating aircraft with very little knowledge of technical, flying or performance issues. That worries some of us. Not you?

IFLY?? Hmmm
 

I am not a pilot, but for those expressing concern that II may be, perhaps the clue is in the name.

What is worrying is that being an OAP appears to be a real bitch.

On the SID charts with which I am familiar, any gradient restriction has a table of GS vs gradient on the same page. This table covers the likely speeds to be encountered.

The question asked by IFLY was "How would a pilot ascertain that climb requirement is going to be met?". The answers so far haven't actually answered the question except perhaps sabenaboy's which alluded to experience being the only way and Intruder alluding to why that is. One way to find your all engine climb gradient, which charts for are difficult to come by, is to find the one engine out gradient and multiply that by 5. That gives a ballpark figure for a twin.

Hi IFLY_INDIGO,
Your NAV display with Constraints will show the ALT required in magenta to make the required gradient. If they appear in amber, then you will need to speed intervene / delay acceleration etc.

- and engine out? What to do then? Does the OP know?

Hi BOAC,
Perform the EO procedure and routing stored in the secondary flight plan (Air Bus SOP).

Doh. :ugh:

You're right, of course, what I worked out was a 7 degree climb gradient, rather than a 7 percent one. :\

IFLY, I presume you are working for IngiGo in India, specifically which airport are you referring to and I can assist you further.

As a side note, look on the company supplied RTOW charts (made using Airbus PEP) you will find that quite a few of them don't even have obstacle data... So you may as well pluck the numbers from thin air as the company has not bothered to pay for a proper obstacle analysis before starting the route.

When IGO started operating some routes in the far NE of India a few years ago they nearly got really burnt because of the lack of an airport study.. Until one of the expats with his own PEP and LPC pointed out to them the shortcomings in their RTOW charts and the fact they had a woefully lacking airport database.