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.

- right cancel ask the Ops Department. This is major. As a pilot you have no way of knowing the climb gradient of your ship at any particular WAT. If proper RTOW analysis has not been done, this airline needs stopping! - you may wish to think again based on the post from ad319! What makes you think there will be one in this airline?

BOAC,

Concur with many of your posts with regards to aviate, and yes, this thread really does appear troubling on many aspects. :eek:

There have been many other discussions on pprune regarding OEI procedures and how the criteria and procedures deal with that situation. :{

EOI in the database? Very, very unlikely. :mad:

You will also find, worldwide, a severe lack of obstacles in the survey. Even in the US, the Part 77 surfaces are limited, and there is no proactive effort to gather obstacles. (note that SafeCo Field was built in the flightpath for Boeing Field, and wasnt even lit. It was the Head of the FAA flying in for a meeting, that wondered about this huge dark spot in the middle of the City)

In most other Countries, it is even worse.

OBN:

As you certainly know, Part 77 is not designed to provide OEI surfaces. It's up to the operators to provide each runway end OEI survey up to the OEI en route flight path.

Indeed it is as to "normal ops" obstacle data. But, no country has obstacle data for OEI.

Very good answer BOAC. Let me say, as always.

terpster,

Yes, this is what I meant by Part 77 being limited. Given that this has been discussed ad nauseum on pprune, I didnt even want to get into OEI stuff...

When I said in most Countries, it is even worse, I was referring to virtually ALL obstacle data, not OEI...

Edit: I would add that given the charting standards and adherence to charting standards, I would consider obstacles on a plate as a courtesy, and would absolutely NOT rely on either the lack of obstacles, nor the obstacles shown, to have any relationship to reality.

IFLY INDIGO
I am sure your operations manual will have something to say on this. Before launching operations from an airfield the company performance engineer using Airbus softwares like PEP or OFP is to ascertain that all these requirements are met. Generally with two engines SID requirements are met. If the gredient is due to terrain issue then OEI perfomance must be checked and OEI SID may have to costructed. There will be company policy on this. If you acedemically want to know then the thumb rules can be used but operationally it is not decision made in the cockpit.

vilas - see post #20? These 'rules of thumb' are actually useless in this case since they only tell you the required RoC and what is needed is the actual, which is NOT available and is well out of reach of any line pilot until they see it when an engine goes pop - which is a little late if you are then over-weight for the required gradient.

IFLY does NOT need 'Rules of Thumb' - he needs performance charts for each SID at each airfield. a_d319 says they are not available and thus as OBN agrees, OEI procedures will not be adequate.

I find this extremely worrying if true. I am also concerned at the number of questions IFLY has asked (including how to fly a circling approach). It raises questions about the training he/she has received both for licence and type.

I use the FCOM climb performance charts on tHe 320 as the predictions on some makes are not accurate. I use them for Kathmandu and they're quite accurate.

I seems there is some misunderstanding here regarding SID climb requirements.

The performance manual from your company will take care of ENGINE OUT climb requirements + a specific procedure to fly in case of an engine failure on that specific SID.

What you see on the SID chart, is a requirement for ALL ENGINES climb gradient, and that is a pilot responsibility to adhere to these. These restrictions are normally due to noise restrictions or for ATC purposes, but can of course also be because of obstacles.

You can NOT use "Rate of Climb thumb rules" here, as you have a segment where you are accelerating.
Instead you need a point, where you have to be at a certain altitude.


You can use this formula :

Required height (ft) = Distance (NM) X (req climb gradient 0,0x) X 6000



Let`s say you need a 4 % climb gradient to 13 NM.

Which altitude at 13 NM ? :

altitude = 13 X 0,04 X 6000
altitude = 3120

3120`

If you do not have a waypoint at 13 NM, create one in your Flightplan and see what altitude the FMS predicts there.



or another example. The SID asks for a 7 % climb gradient to 8000`

At what distance from departure do I need to be at 8000´ ? :

8000 = distance X 0,07 X 6000
8000 = distance X 420
8000/420 = distance

19 NM

again, create a waypoint at 19 NM, and see if the FMS predicts to be at or above 8000`there.


Easy

- I refer you to post #20 as well.

While your use of the FMS is good, it does not tell IFLY what RTOW he/she can use on a particular day and SID, does it? By the time the boys and girls get their stickies on the FMS and start making new waypoints the a/c will have been loaded.

BOAC

Off course you need the correct GMC for your specific RWY of DEP, to satisfy the ENGINE OUT climb requirement. You can NOT calculate that yourself !

My input were for the ALL ENGINE SID climb requirement, which is the responsibility of the pilot to comply with.
Even though many pilots are not aware of that, and do not know how to make that simple calculation, which is very easy and fast to make (even for an old man like me ;-)

so what's the answer?
 

So irrespective of what analysis airline has done, there is no way for a pilot to ascertain on the ground (using chart/table) that he would be meet the climb gradient requirement of SID? experience or FMGS prediction (magenta/amber as suggested by rudderrudderrat) is the only way out?

using the formula GS * % climb gradient, does not sound the right way to ascertain the climb performance on ground. it doesn't include the available thrust, OAT, PA, actual takeoff weight in the calculation, which my common sense tells should be the part of calculation. After all, we can be flying level with any of the GS mentioned on the chart!

Unless there are particular obstacle problems on a particular SID, you can pretty well assume that as long as you are below WAT limits you will achieve normal climb gradients on all engines. It is engine out that is the governing consideration for which you need an airfield analysis.

A climb gradient requirement is not the same as an altitude restriction at a certain point. When the chart says that a 7 % climb gradient is required up to 7000, that means that you should stay above this slope all the time! Theoretically it could be that you make the restriction at 7000 ft with more then a 7 % average climb rate, BUT you might have gone below the required slope during the acceleration phase to get your flaps up.

So, as I said in my previous post: "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"

no restricting altitude
 

There was no restricting altitude in my original post. I am referring to few RNAV SIDs of VABB and VIDP. only climb gradient requirement is mentioned.

IFLY_INDIGO

We are talking about two things here.

Engine failure
Your company Performance Manual will (hopefully) have a correct calculated max T/O Mass for each RWY you are flying from. This gives you the max T/O Mass + procedure, so you will able to safely fly up to a safe altitude in case of an engine failure = it keeps you away from obstacles


All engine T/O
Here you as a pilot have to calculate and comply with the restriction laid out in the SID. These restrictions can be due to noise restriction, ATC or obstacles. Use the formula I wrote earlier.


You can NOT do what "rudderrudderrat" wrote earlier :

"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."

because very often these restrictions are not in your FMS as a waypoint/restriction.

climb angle?
 

Jaja, your method is good. I have noted it down to try.

7% climb gradient turns out to be 3.99 deg of climb angle. of course, we can use FPV one side to be ascertain that we are meeting the requirement, but that is only possible in-flight.

Hi jaja,
Then insert a "+ALT" restriction.

BOAC

Not to be personal, but considering your post # 7 talking down to AIRBUS pilots, and now # 33, there is no such thing for a professional pilot as to "ASSUME" in cases like these ;-)

BOAC : "you can pretty well assume"


rudderrudderrat
Quote:
"because very often these restrictions are not in your FMS as a waypoint/restriction.
Then insert a "+ALT" restriction"
That is also what I wrote earlier, but you have to make the calculation first, and then create a waypoint.

Sabenaboy
You can NOT just delay the acceleration fase. In your Performance Manual you have a Maximum Acceleration Height (this is to complete the 3rd segment before end of the 10 minute T/O thrust limit). I think also you are mixing things up. Your example with a 7 % climb requirement, is an AVERAGE of 7 %, so it CAN include the acceleration fase. Read the previous posts again, and you will see we are talking about two different things here ;-)

- nothing to take 'personally', jaja since I am not aware of talking 'down' to AIRBUS pilots in #7 or #33 and in fact to introduce 'Airbus paranoia' into this non-type-specific thread takes some doing! Do you see monsters behind settees as well?

Regarding 'assume', I take it you still have not looked at #20? I recommend you do soonest. How else can +IFLY work it out? Any ideas? (non-type-specific, of course:ugh:)