2.4% regulatory climb gradient for single engine

[HazelNuts39]

which bit of Maximum Allowable Takeoff Weight do people have a problem with?

Two bits actually:

- Climb requirements: The maximum takeoff weight limited by climb requirements, commonly referred to as WAT-limit, provides a gradient of not less than 2.4% for twins at the point where the landing gear is fully retracted, OEI. It is an operating limitation under Part 91, except for Skky.

- Obstacle clearance requirements: Obstacle clearance is not a certification requirement. The certification requires that the AFM provides information on the Net flight path, and FAR part 121 requires its use to ensure obstacle clearance, but Part 91 does not.

FAR Sec. 25.1533

Additional operating limitations.

(a) Additional operating limitations must be established as follows:
(1) The maximum takeoff weights must be established as the weights at which compliance is shown with the applicable provisions of this part (including the takeoff climb provisions of Sec. 25.121(a) through (c), for altitudes and ambient temperatures.
(2) (...)

[aterpster]

Bizjetjock:

Added to which, in my book I'm being paid to keep the boss safe - and he thinks so too. He would probably be mightily unimpressed (= me fired) if he though I was gambling with his and his family's safety.

Then, he doesn't mind paying a professional performance and engineering company to do a full assessment for each runway you use, including an OEI flight path. Unfortunately, not everyone sees the value of such a service.

[mutt]

Unfortunately, not everyone sees the value of such a service.

But more and more operators are starting to see that value. Skky's reading of FAR91 might be correct, but the interpretation is not. Why is it that the Honeywell FMS has WAT climb limits under FAR91, surely if it wasn't required, Honeywell wouldn't have invested the money into validating the data?

Mutt

[aterpster]

mutt:

But more and more operators are starting to see that value. Skky's reading of FAR91 might be correct, but the interpretation is not. Why is it that the Honeywell FMS has WAT climb limits under FAR91, surely if it wasn't required, Honeywell wouldn't have invested the money into validating the data?

When Honeywell designs a system, say for a Falcon 900EX or G550, they do not know whether the operator will be Part 91, 121, or 135.

There is no FAR 121.189 equivalent in Part 91. If the AFM made the flight path necessary for all Part 25 airplanes operated by U.S. operators then there would be no need or reason for 121.189 (or its Part 135 equivalent).

[galaxy flyer]

I think BizJetJock has it precisely correct. FAR 91 requires compliance with AFM limitations; FAR 25 AFMs require OEI climb out flight paths, hence you must meet the paths, by some means. I read thru the AFMs of the three types I'm familiar with and they all say pretty much what he posted.

GF

[Zeffy]

Subpart G—Additional Equipment and Operating Requirements for Large and Transport Category Aircraft

§ 91.605 Transport category civil airplane weight limitations.

(a) No person may take off any transport category airplane (other than a turbine-engine-powered airplane certificated after September 30, 1958) unless—

(1) The takeoff weight does not exceed the authorized maximum takeoff weight for the elevation of the airport of takeoff;

(2) The elevation of the airport of takeoff is within the altitude range for which maximum takeoff weights have been determined;

...
...
...

(c) No person may take off a turbine-engine-powered transport category airplane certificated after August 29, 1959, unless, in addition to the requirements of paragraph (b) of this section—

(1) The accelerate-stop distance is no greater than the length of the runway plus the length of the stopway (if present); and

(2) The takeoff distance is no greater than the length of the runway plus the length of the clearway (if present); and

(3) The takeoff run is no greater than the length of the runway.

[Pugilistic Animus]

It is probably more economical to hire a performance companythan it is to back off the weight to meet the DP gradients OEI

However although not explicitly written in part 91 I can almost guarantee that if an incident occured...and you got too close to an obstacle for a near CFIT...they'd nail you with a 91.13

[Zeffy]

However although not explicitly written in part 91 I can almost guarantee that if an incident occured...and you got too close to an obstacle for a near CFIT...they'd nail you with a 91.13

When has that ever happened?

Got a cite?

NTSB Adjudication?

Or not really a "guarantee"?

[FlightPathOBN]

PA,

You must fly out of TEB!
That is why Sulley decided to land in the Hudson than divert to TEB, he didnt want an OEI 91.13 violation!

[Pugilistic Animus]

I'm writing from my phone again...so please excuse me

ZEFFY...the DOT is the worst of all government beauracracies...so if the FAA can find a reason for enforcement they will...although i can think of any enforcements as described...when i read some other action taken by the faa i just would be surprised...so it's just my best guess at what they may do...but i wouldn't chance...i think 91 operators should at least try to make the DP oei...just sounds responsible to me..

FPOBN...I have not seen TEB since 07 iirc....but Im not sure what you mean regarding sully???....:-)

[mutt]

Considering that FAR91 was written for FAR 23 and FAR 25 aircraft, it stands to reason that they didn't cite climb gradients, however for those of us operating FAR 25 large aircraft, with safety management systems, safety factors, oversight authorities, noise requirements and SAFA, we cannot operate as per the letter of FAR91, it just isn't acceptable. We have takeoff performance issues with SAFA while in full compliance with FAR121

Sully means Captain Chesley `Sully' Sullenberger III, the Captain of U.S. Airways Flight 1549.

Mutt

[Zeffy]

..i think 91 operators should at least try to make the DP oei...just sounds responsible to me..

Far more responsible would be to engage the services of a profession performance engineering company whose runway analysis products are compliant with AC 120-91.

With respect to the opinion that "making the DP OEI" would be a good idea, what would the advocate of such a solution propose to do at KLAS on the COWBY4 SID?





`


As indicated by this recent article published by NBAA, numerous problems arise when an operator attempts to apply AFM data to a SID or ODP -- e.g., failure to consider low, close-in obstacles and invalid calculations due to time limits on takeoff thrust, etc.

[kellykelpie]

I find Pprune can be a very interesting resource at times and this thread certainly proves it. It's great to have such a broad knowledge base - thanks to J.T for explaining what I consider a complex subject.

[aterpster]

P.A.:

However although not explicitly written in part 91 I can almost guarantee that if an incident occured...and you got too close to an obstacle for a near CFIT...they'd nail you with a 91.13

How would the feds know that someone got "too close" to an obstacle?

And, are you speaking of all engines operating or OEI?

[aterpster]

Mutt:

Considering that FAR91 was written for FAR 23 and FAR 25 aircraft, it stands to reason that they didn't cite climb gradients, however for those of us operating FAR 25 large aircraft, with safety management systems, safety factors, oversight authorities, noise requirements and SAFA, we cannot operate as per the letter of FAR91, it just isn't acceptable. We have takeoff performance issues with SAFA while in full compliance with FAR121

The standard of care in the performance arena required from a regulatory standpoint is simply different for commercial and private flight operations. And, you are right, even with Part 121 operators who meet the minimum standards set forth in 121.189 can easily have a CFIT with OEI. The industry has been spared most of this in the turbine era because of the fantastic reliability of the powerplants.

[aterpster]

For many years the FAA would not permit commercial operators to make IFR takeoffs on Runway 18 at South Lake Tahoe, California. (KTVL). A few years ago a different "performance" decision was made by the FAA. Below are today's takeoff minimums and ODP (obstacle departure procedure) for KTVL.

The takeoff minimums notwithstanding, a compliant takeoff flight path analysis is weather independent. I wonder how even the best takeoff performance engineering company could provide a safe takeoff flight path for this runway. The splays recommended in AC 120-91 would limit payload considerably more than application of the minimum requirements of FAR 121.189. But, a minimum 121.189 path would likely result in a OEI CFIT crash. Or does the modern performance engineer provide an RNAV track that is somewhere between the minimum requirements of 121.189 and the splays of AC 120-91. And, even applying the splays of AC 120-91 is containment assured without positive course guidance out of this canyon?

[mutt]

Zeffy...... under 121, we would go straight ahead and account for the obstacles in the flight path, if we didnt get sufficient operational weight doing that, we would design a single engine flight path to avoid limiting obstacles.... we wouldnt attempt to follow the SID with an engine out as the payload would be too severely penalised.

Mutt

[Zeffy]

Mutt - thanks.

Actually, I wasn't advocating flying a SID OEI -- just pointing out the impracticality with the KLAS example.

Due to misinformation promulgated by FAA Part 142 training outfits over the years, many corporate operators have been lead to believe that they need to be able to fly a SID/ODP following the loss of an engine. Simply not true.

[mutt]

aterpster, how about "immediate right turn at DER to SHOLE and hold, max speed in turn 160 KIAS".

But based on the noise restrictions, we wouldn't be allowed in there anyway

Mutt

[aterpster]

mutt:

aterpster, how about "immediate right turn at DER to SHOLE and hold, max speed in turn 160 KIAS".

I don't think so. Check the topo.

Runway 36 is the calm wind runway. In fact, the airport manager recommends 36 so long as tail wind limitations aren't exceeded.