Density altitude legality question

[Brian Priest]

Hello all, I probably should know this, but I am looking for a reference concerning the Density Altitude in the performance section of the POH.

Basically in the arrow I rent, there is a note in the takeoff performance about the density altitude and do not extrapolate above 7000 feet.

My question is: for a part 91 flight, is it legal to depart with a DA above any values listed in the performance section?

Believe me, Im aware of all the safety aspects of high density altitudes. Im looking for what the legal side is. Ive seen quite a number of debates on the topic, but looking for the location I can look to see the answer myself. And yes I am up to speed on the reg stating I need to become familiar with all available info.

Thanx much!

 

[murphey]

If there were a legal limitation on cherokee/archers, those of us who don't live in the flatlands would be grounded 4-6 months of the year. Right now, DA on the ground is over 8500 msl every day.

 

[mscard88]

Always fits in a few Part 91 rules, like careless operation, pre flighting, etc. but I know of no specific legal rule. There may be one I don't know.

 

[Brian Priest]

Exactly my point! Lol, I’m sure it’s fine, but I wouldn’t want to put myself on the FAA radar

 

[bobmrg]

If I recall correctly, limitations are in Section 2 of the POH. If you don't see anything there, there is no limitation.

Bob

 

[denverpilot]

I can’t think of an older airplane manual that doesn’t require extrapolation at KLXV at 70F.

 

[murphey]

I can’t think of an older airplane manual that doesn’t require extrapolation at KLXV at 70F.

Oh please....unless you're a turbo or big twin, you're not gonna take off at 70f at KLXV. Right now, 9 pm MDT, temp is 60f, DA is 12,000 msl. Altho you might be able to take off, aint gonna get much climb to get over the hills in any direction.

 

[RyanB]

Basically in the arrow I rent, there is a note in the takeoff performance about the density altitude and do not extrapolate above 7000 feet.

My question is: for a part 91 flight, is it legal to depart with a DA above any values listed in the performance section?

 

[EdFred]

Oh please....unless you're a turbo or big twin, you're not gonna take off at 70f at KLXV. Right now, 9 pm MDT, temp is 60f, DA is 12,000 msl. Altho you might be able to take off, aint gonna get much climb to get over the hills in any direction.

I did an 11400 ft density altitude takeoff in PA28. Another 600 foot would have been doable.

 

[denverpilot]

Oh please....unless you're a turbo or big twin, you're not gonna take off at 70f at KLXV. Right now, 9 pm MDT, temp is 60f, DA is 12,000 msl. Altho you might be able to take off, aint gonna get much climb to get over the hills in any direction.

I DID take off at 70F at KLXV. LOL!

Lightly loaded 182, and the foreknowledge that the departure climb would be like a high altitude cruise climb... beyond anemic.

Uses lots of runway too. We were off by a little over halfway. Our must abort point was halfway if the airspeed didn’t come up and 2/3s if it just didn’t want to fly off on its own. I was ready to stand on the brakes and bring the fun to a halt.

It so rarely gets to 70F up there it was a surprise that day. We were expecting about 65F.

Anyway... 70F also used to be the “no go” if above that for the CPA airport tour when coming out of LXV. Don’t know if they’ve modified it but I wouldn’t recommend it in anything with less than 200HP at sea level.

CFI and I were chuckling that it would be my luck to be right AT the limit. A good training exercise.

Climb rate was about 200’/min.

 

[Clip4]

Hello all, I probably should know this, but I am looking for a reference concerning the Density Altitude in the performance section of the POH.

Basically in the arrow I rent, there is a note in the takeoff performance about the density altitude and do not extrapolate above 7000 feet.

My question is: for a part 91 flight, is it legal to depart with a DA above any values listed in the performance section?

Believe me, Im aware of all the safety aspects of high density altitudes. Im looking for what the legal side is. Ive seen quite a number of debates on the topic, but looking for the location I can look to see the answer myself. And yes I am up to speed on the reg stating I need to become familiar with all available info.

Thanx much!

91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—

(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

Since the chart will not allow you to determine take off data and comply with (b)(1), you would be illegal.

 

[dmspilot]

91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—

(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;

(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

Since the chart will not allow you to comply with (b)(1), you would be illegal.

Garbage.

Being familiar with the information, and the information not existing, are entirely different concepts. The regulation does not require you to know information that doesn't exist.

 

[3393RP]

While it says "Become familiar with", there's no language which says reliance upon and compliance with the given takeoff and landing distance data is legally required.

That's how I read it.

 

[Brian Priest]

Well see, that’s my point. I became “familiar” with the data, lol there is none! See? familiar.

In just a few posts, no consensus. That’s why it’s so tricky. Does no data mean no go? In 121 world, no go. In 91 world, where we can “take a peek”, different story.

So I guess it boils down to, careless and reckless or excercise the privileges of part 91.

 

[midlifeflyer]

@murphy made the main point. There are parts of the country in which even FAA inspectors take off above book number altitudes much of the year. By some folks definition, I guess I was careless and reckless most of my 20 years in Colorado!

The warning against extrapolation is simple. Density altitude affects different aircraft systems - engine, wings, prop - in different ways and the cumulative effects are not really linear. So extrapolation is not reliable. No book value means "be careful." Use the accumulated knowledge of those who fly regularly in high density altitude environments. Learn to lean properly. Use the 70/50 rule and don't fudge the abort point. Recognize the effect on perception of speed and, particularly on takeoff, climb speed, attitude and profile. Although I didn't use it much personally, even the FAA recognizes the value of the Koch chart for getting nonpublished ballpark numbers (FAA, Density Altitude).

Oh yeah. One more. Don't screw up something pretty simple that is done every day. If you cause a problem due to ignorance in high density altitude ops, "careless and reckless" is likely (assuming you survive). But it won't be because Cessna didn't give you the data. I'd guess most of the takeoff and landing accidents at high density altitude airports are not about the lack of a length number in the manual.

 

[Clip4]

§ 91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include -



b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.

Piper specifically says, “Warning. Performance information derived from extrapolation beyond the limits shown of the chart should not be used for flight planning purposes.”

The reg requires you to be familiar with all information. A warning is information.

If you have a DA accident in an aircraft where you opted to take off without reviewable date you are going to be violated for this section and reckless op.

You saw Canadair ground it’s fleet in Phoenix last year for the same situation.

 

[Brian Priest]

Midlifeflyer, I like that FAA ref to the Koch chart. I noted that they said the AFM/ POH should be referenced if not use the Koch chart. Well, there is no values above 7000 in the arrow, so Koch chart! Lol

Incidentally, even though the arrow says do not extrapolate above 7000, the lines piper drew go up to 7800.

 

[AKBill]

First time I've seen the Koch chart, interesting. Guess I'm lucky the DA in Juneau is normally a negative number.....

 

[MauleSkinner]

§ 91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include -



b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.

Piper specifically says, “Warning. Performance information derived from extrapolation beyond the limits shown of the chart should not be used for flight planning purposes.”

The reg requires you to be familiar with all information. A warning is information.

If you have a DA accident in an aircraft where you opted to take off without reviewable date you are going to be violated for this section and reckless op.

You saw Canadair ground it’s fleet in Phoenix last year for the same situation.

No, you saw Canadair ground its fleet in Phoenix because the airplane's have a temperature limitation in AFM Section 2 of (probably) ISA+35 degrees C for takeoff and landing, and very likely a limitation that says you have to be in compliance with a couple of charts for takeoff. There are no such limitations in most CAR3/Part 23 airplanes.

 

[Lindberg]

§ 91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include -



b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.

Piper specifically says, “Warning. Performance information derived from extrapolation beyond the limits shown of the chart should not be used for flight planning purposes.”

The reg requires you to be familiar with all information. A warning is information.

If you have a DA accident in an aircraft where you opted to take off without reviewable date you are going to be violated for this section and reckless op.

You saw Canadair ground it’s fleet in Phoenix last year for the same situation.

You changed your answer somewhat, but it is still incorrect for a part 91 flight. Note the very different language in part 121:

§121.177 Airplanes: Reciprocating engine-powered: Takeoff limitations.
(a) No person operating a reciprocating engine powered airplane may takeoff that airplane unless it is possible—

(1) To stop the airplane safely on the runway, as shown by the accelerate stop distance data, at any time during takeoff until reaching critical-engine failure speed;

(2) If the critical engine fails at any time after the airplane reaches critical-engine failure speed V1, to continue the takeoff and reach a height of 50 feet, as indicated by the takeoff path data, before passing over the end of the runway; and

(3) To clear all obstacles either by at least 50 feet vertically (as shown by the takeoff path data) or 200 feet horizontally within the airport boundaries and 300 feet horizontally beyond the boundaries, without banking before reaching a height of 50 feet (as shown by the takeoff path data) and thereafter without banking more than 15 degrees.

So part 121 requires you to actually have all this data. Part 91 doesn't. If you're familiar with the warning in the piper poh and have taken it into consideration, that's what 91.103(b) wants you to do.

 

[murphey]

§ 91.103 Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include -



b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:

(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and

(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.

Piper specifically says, “Warning. Performance information derived from extrapolation beyond the limits shown of the chart should not be used for flight planning purposes.”

The reg requires you to be familiar with all information. A warning is information.

If you have a DA accident in an aircraft where you opted to take off without reviewable date you are going to be violated for this section and reckless op.

You saw Canadair ground it’s fleet in Phoenix last year for the same situation.

There have been numerous times at Phoenix and Las Vegas, NV when various commercial carriers called up the Boeing engineers about the temps in the summer. Most of the time, the answer was to offload weight. A few times, it was " stay on the ground ".

 

[flyingcheesehead]

If I recall correctly, limitations are in Section 2 of the POH. If you don't see anything there, there is no limitation.

I'm with Bob on this one. I believe that Section 2 is the only part of the manual that's actually certified and binding.

Oh please....unless you're a turbo or big twin, you're not gonna take off at 70f at KLXV. Right now, 9 pm MDT, temp is 60f, DA is 12,000 msl. Altho you might be able to take off, aint gonna get much climb to get over the hills in any direction.

Bah. I took off from KLXV in a normally aspirated 182 at a DA of 12,200 feet. That runway is plenty long. Our ground roll was about 2,000 feet (about 3x normal).

 

[denverpilot]

Bah. I took off from KLXV in a normally aspirated 182 at a DA of 12,200 feet. That runway is plenty long. Our ground roll was about 2,000 feet (about 3x normal).

Heh. It’s not the length for liftoff that’s the problem there, it’s the distance from be liftoff point to the tree line to the north that had us wondering, with only a 200’/min climb rate at Vx.

Old CFI joked, “If you ever need it, there’s a gap in the trees over there to the left. I needed it once.”