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Old 11th Jul 2011, 19:50   #1 (permalink)
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Join Date: Nov 2002
Location: Sandpit
Posts: 107
Climb Gradients


I know climb gradients for instrument departures have been discussed in the past but could not find this particular question on the forum.

We all know that the minimum climb gradient for a SID is 3.3% (2.5% net) unless otherwise specified on the chart. An aircraft is required to meet that climb gradient on 2 engines for a twin engine aircraft.

What most operations manuals will state is that SID should only be accepted if the required climb gradient can be maintained on 1 engine, or a company single engine climb out contingency procedure is in place in the event the required climb gradient cannot be met on 1 engine.

The climb requirement of the SID should be maintained until the completion of the SID or at the very least, until reaching an altitude at or above the MSA.

The part 23 aircraft has a second segment climb requirement of 2% and then a 1.2% requirement at 1500ft. When operating in the summer, if we were to lose an engine immediately after departure at MTOW we will be operating to the limits of performance charts (ie 2%) and no more.

Many airlines have detailed single engine climb out procedures for every airport they fly out of, and a team of skilled staff in operations detailing these procedures in the ops manual and aircraft FMCs. We do not have these luxuries, and the only reference to a contingency procedure makes reference to the use of VFR charts.

Finally, here come my questions. For example, when departing a runway in 500m RVR with an accompanying SID with a climb gradient of 3.3%, I explain I cannot accept the procedure. This covers the legal aspect of accepting the SID without having a VFR contingency procedure. The ATC gives us a clearance of maintain runway heading until 4000ft, further clearance as per radar. With this procedure, what sort of obstacle protection have I been given? If I lose an engine after departure, I can climb at 2% , but is that enough to comply with this ATC departure? Is there a protected area around the field to guarantee obstacle clearance to 4000ft?

At one airport we depart from we always get given a runway heading 3000ft departure and don't even get offered a SID. But within 5NM there is a city skyline reaching 1000ft.

I have heard of a standard 200ft requirement per NM mile, but cannot find any regulatory material stating this.

I would like to come up with a guideline for our pilots flying Part 23 aircraft and detail contingency procedures for runways we depart from. I would also like to explain what guarantees on obstacle clearance they are getting when departing in IMC on a straight ATC departure.

A great thanks in advance for your replies.


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Old 7th Aug 2011, 11:53   #2 (permalink)
Join Date: May 2008
Location: dubai
Age: 45
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Really the question is are you protected for the climb gradients on a radar vector from take off to the MINIMUM Vector Altitude. I would definitely say NO. The proof is that a company can have an Engine Inop Procedure with an immediate turn after take-off, while ATC might still give the aircraft a "maintain runway heading" vector. In that case, if you were to blindly maintain runway heading with an engine out, and not follow the EO Procedure, obstacle clearance might not be assured.. you know what i mean..

Last edited by stormyweathers; 7th Aug 2011 at 13:46.
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