Performance / obstacle clearance
 

In our manuals it says that in case of an engine failure :our performance calculations will take into account all obstacles within 600 meters of either side of the runway extended centreline.
Our manuals also state that for the Sim check we need to fly headings/tracks within the tolerance limits of +\- 10 degrees for single engine.
On a wide body jet if you deviate +\- 10 degreee you will not stay within the 600M "protected area " for long !
I know that the limitations -/+ 10 degrees are for skill test/Check and the obstacle clearance limits of 600 M are for the Pan Ops regulatory but aren't they suppose to compliment each other ?

Not to mention that many a present day L-NAV systems struggle to keep a magenta line within 0.3 NM if conditions are less than ideal.

Hopefully your obstacle / escape route specialist allowed for more error than the regulatory 600 m. Anybody ready to calculate how wide is 1 deg angular of a VOR-radial, let's say, at 5 miles out?

0.087269 miles :}

Fortunately, most Part 121 operators voluntarily used AC 120-91, "Airport Obstacle Analysis."

https://www.faa.gov/regulations_poli...cumentID/22479

I forgot to mention that our aircrafts are old 1984 classics WITHOUT GPS - we are only RNAV 1 compliment !
According to my calculations if you are very heavy and it's a hot day it will take you about 10 NM to climb to 1500' AAL. According to my calculations ( using TANgent ) you need to ensure that you track with an accuracy of 1.8 degrees to ensure you do not exceeed the 600meters wide protected area for the 10 NM climb to 1500' ! Am I correct ?

camps:

Back in the 1980s we challenged our company's performance assumption. An honest VP agreed to provide the pilot's union with performance data for OEI on Runway 25 at KLAS. We picked the temperature that would just permit a MGTOW for the 727-200 with the 14,500 thrust engines. It took 31 miles to reach 1,500.

:eek: And here's me thinking you guys could leap tall buildings with a single bound. :eek:

According to my calculations if you are very heavy and it's a hot day it will take you about 10 NM to climb to 1500' AAL

VERY optimistic ...

MGTOW for the 727-200 with the 14,500 thrust engines. It took 31 miles to reach 1,500.

I have a relevant AFM in the files somewhere but I don't think I'll go searching. This is a bit more realistic. Now, if you go to the twins, where things are abysmally worse .. it can be a LOT more .... DC9, for instance, with a long third segment .. could take 50-odd nm. This is why we continually keep pushing the "don't try to wing the obstacle clearance visually on the fly ..".

And here's me thinking you guys could leap tall buildings with a single bound.

.. that's a skill reserved for you flingwing folks ..

J.T.:
Well, if the crew does that on a nice clear day, they may get a spectacular view of the forthcoming point of impact.

We don't even get a mention John.

The Airline Transport Rated Pilot

Leaps tall buildings in a single bound
Is more powerful than Concorde
Is faster than a speeding bullet
Walks on water
And discusses policy with God.

The Multi Engine Rated Pilot

Leaps short buildings in a single bound
Is more powerful than a VC10
Is as fast as a speeding bullet
Walks on water on a calm day
And talks to God.

The Instrument Rated Pilot

Leaps short buildings with a running start and a favourable wind
Is almost as powerful as a 1-11
Nearly as fast as a speeding bullet
Walks on the water of a deep puddle
And talks to God, if specially requested.

The Commercial Rated Pilot

Leaves nail scratch marks at the top when trying to leap short buildings
loses a tug of war with a 152
Can fire a speeding bullet
Swims well
And is occasionally addressed by God.

The Private Pilot

Barely clears a scout camp tent
Is run over by a single engine aircraft
Sometimes recognizes a speeding bullet
Can dog paddle
And talks to animals.

The Soloed Student Pilot

Runs into buildings
Recognizes a Cessna 152 twice out of three times
Has never seen a speeding bullet
Can stay afloat under instruction
And talks to the wall.

The Non-Soloed Student Pilot

Trips over door sills entering buildings
Says "gosh, look at the aeroplanes" a lot
Doesn't know what a speeding bullet is
Only stands in the shallow end
And mumbles to himself.

The Aircraft Engineer - that's you John

Lifts buidings and walks under them
Kicks aircraft out of hangar
Catches speeding bullets with his teeth and chews them
Freezes water with a single glance
And talks to everybody
THE AIRCRAFT ENGINEER IS GOD

I was actually thinking 727 performance in my post, didn't realise it could be so dismal.

Sorry guys I should have mentioned the type of aircraft : it's the 767 with the old vintage A1 engines

they may get a spectacular view of the forthcoming point of impact.

Granted ...

We don't even get a mention

Hadn't seen that particular version previously .. love it.

it's the 767 with the old vintage A1 engines

Long time since I looked at 767 performance so the memory is a tad scratchy. If you have an AFM, perhaps you could redo the sums and see what the story might be ? Twins don't go all that well at WAT limited weights.

Megan: It's been a while since I heard/read that old soliloquy. Love the dreams & wishes.

Would appreciate if anyone would shed some light on how are we are suppose to keep that aircraft within the allocated protected area ( 600M left and right of the runway centre line ) during the single Eng climb ? Our HSI is not calibrated / scaled in 100s of meters ? The minimum range setting is 10NM . We also don't have GPS :(

Under 14CFR 121 obstacles must be cleared vertically by 35' or 200' horizontally within the airport boundaries and at least 300' horizontally after passing the boundaries

camp
I think you're over thinking this.
Most 767s will depart on a runway analysis that accounts for obstacles in the departure. If there is a special engine out procedure it's usually stated on the runway analysis as well. They usually cover PANS-OPS or TERPS.
If you lose one on takeoff, fly the Boeing profile, clean up and climb to a safe altitude (refer to the runway analysis, SID, or mark 1 eyeball)
Also, on one engine you're likely a pan pan or a mayday so all bets are off. The regulator says do what you need to do. Anyone taking measurements in this circumstance can get stuffed. Unless you can't control your heading and yaw manually within reasonable tolerances. If you can't, center-in-command, heading mode. LNAV, VNAV works too.

shed some light on how are we are suppose to keep that aircraft within the allocated protected area

That comes under the title of training and proficiency which comes down to sim practice .. if you are fortunate enough to have an employer who puts dollars into extra training in the box.

Forget the eyeball .. gradients are too small to estimate and, with the body angles, how do you see over the nose in any case ?

Other boxes can be useful .. eg, backcourse LLZ tracking (a very useful sim training exercise to get the stick and rudder skills up ... try a min weight, aft CG, failure during the rotation with a requirement to so track) ... and, these days, preprogrammed FMS escapes may be useful.

I think you're over thinking this.

I don't think so at all. There be dragons outside the splays

fly the Boeing profile,

However, the Boeing profile doesn't put you in the middle of the splay, that's a pilot task and responsibility.

Anyone taking measurements in this circumstance can get stuffed.

Of course they can.

However, the aforementioned dragons can be right on the splays. It is not at all uncommon to run the splay up the side of the mountain so that the sums work out. If Captain Speaking allows his/her aeroplane to diverge too much then it's all over, Red Rover.

J.T.

I believe most U.S. Part 121 carriers' Performance and Engineering departments use the dimensions in AC 120-91 (Post #4), rather than the lateral limits of 121.189.

I know that APG uses the lateral areas of AC 120-91.

There exist various standards for splays but the skill matter remains critically important.

Many years ago, a local Regulatory certification/ops engineer (Ian C, if my recollection be correct) organised for a simulator study to be run with the two major domestics over here. Typically, a minimal briefing on the exercises he wasn't interested in .. and, I suspect, no mention of any engine failures. I note that Ian, for whatever reason, had missed out on getting into the airlines as a pilot ... but he was certainly a sufficiently experienced flyer to understand the significance of the study.

In amongst the distraction exercises, V1 failures were introduced and the subsequent flight paths tracked. I still have a report on the exercise tucked away somewheres and the graphed tracks are interesting, to say the least.

I don't recall the sample size but it was more than reasonable for drawing some inferences. While the great majority were fine, there was a fairly small number which indicated that the pilot flying was away doing something else at the time or, for whatever reason, just having a bad day ... it wouldn't have mattered what the splays were ..

Now this was with two airlines (in a commercially protected environment) both of which indulged in significant "over training" compared to what we see these days ...

Obviously there was some post study navel gazing to the airlines' benefit ...

... food for thought in our current minimalist training environments ?

j.t.:

Even TERPs and PANS-OPs normal operations criteria cannot protect for errant blunders.

Having said that, the more modern birds that automatically input the correct amount of rudder for an engine failure on takeoff, and which are capable of both RF legs and RNP accuracy, integrity, and continuity as low as RNP 0.10, could have RNAV/RNP OEI flight-paths that could eliminate the need for splays. Just linear step-up in 2xRNP containment areas, similar to what is done today for RNP AR missed approach procedures.