takeoff distance factor

[japesaar]

Do I need to take the takeoff distance factor in consideration when calculating the maximum takeoff weight?

I know that after using the takeoff graphs to calculate the takeoff distance required I need to multiply the distance by 1.15 (I am learning on a C172). Do I need to do the same when calculating the maximum takeoff weight? (when TODA is given divide it by 1.15?)

Thank you in advance...

[forever flying]

The takeoff distance factor should be already calculated in charts.

Check the corner of the chart, it should state the factor as 1.15, therefore it need not be calculated a second time. :)

[vieuphoria]

If you are using a FAA take off chart that does not state on the performance data that there is a safety factor, then you will have to apply the 1.15 ie if TODA is 1000M and your performance chart does not have a safety factor then you would need to ammend the take off distance ie 1000/1.15 = 869M on your chart, or put another way, once you have calculated the distance required *1.15 =<1000M then you are good to go!

[Bladeangle]

CAO 20.7.4 outlines what is required.

[Grogmonster]

Just have a quick check on the CASA website because I think there is a CAAP just out that deals with CAO 20.7.4 and a one or two others. More rules by stealth.

Groggy

[MakeItHappenCaptain]

Orright, kiddies,

Everyone except for Bladeangle :=

If you are using the almost non-existant old CASA flight manuals (ie. the typewritten, tell you next to nothing, kept in a crappy old A5 folder type which CASA has been gradually phasing out totally), then they will say that they include the factor (which may be in excess of 1.15 if the aircraft has a heavy enough MTOW).

If there is a page at the start of the flight manual that shows the factory manual is the approved flight manual (which should be just about anything from the late seventies onwards by now unless your school is stuck in the stone age) then the factory figures (without any factor) are the figures to be used.

6.3 Where there is an approved foreign flight manual or a manufacturer’s data manual for an aeroplane that sets out the take-off distance required for that aeroplane, then that aeroplane must be operated so as to comply with either the requirements set out in paragraphs 6.1 and 6.2 or the requirements relating to take-off distance set out in either of those manuals.

Note: The data contained in some manufacturers’ data manuals is unfactored and makes no allowance for degraded aircraft performance. Where there is a considerable difference between the data in a manufacturer’s data manual and the data in the flight manual for the aeroplane then the manufacturer’s data should be treated with caution.

Once again a case of flying schools completely out of touch with the real world.:rolleyes:
If you tell your CP that your Caravan won't be going to a strip because you don't have the CASA safety factor, they may not be very impressed.

And before everyone starts jumping on the "but those figures are obtained by a brand new aircraft with a test pilot" bandwagon, here's another myth gone...

FAR 23.45 (one of the rules FAA aircraft are certified under)
These procedures must be able to be executed consistently by pilots of average skill in atmospheric conditions reasonably expected to be encountered in service.

[Stretch06]

Groggy,

The CAAP was release and then removed just as quick. Email from CASA late last week stating it wasn't ready for release yet.

Stretch

[Two_dogs]

Just to expand on MakeItHappenCaptain's post. Disregarding the CASA Flight Manuals, it is stated here;

CAO 20.7.4

6 TAKE-OFF DISTANCE REQUIRED
6.1Subject to paragraph 6.3, the take-off distance required is the distance to accelerate from a standing start with all engines operating and to achieve take-off safety speed at a height of 50 feet above the take-off surface, multiplied by the following factors:
(a) 1.15 for aeroplanes with maximum take-off weights of 2 000 kg or less;
(b) 1.25 for aeroplanes with maximum take-off weights of 3 500 kg or greater; or
(c) for aeroplanes with maximum take-off weights between 2 000 kg and 3 500 kg, a factor derived by linear interpolation between 1.15 and 1.25 according to the maximum take-off weight of the aeroplane.
6.2For aeroplanes operated on land, take-off distances are to be determined for a level short dry grass surface. For aeroplanes operated on water, take-off distances are to be determined taking into account the maximum crosswind component and the most adverse water conditions for the aeroplane type.
6.3 Where there is an approved foreign flight manual or a manufacturer’s data manual for an aeroplane that sets out the take-off distance required for that aeroplane, then that aeroplane must be operated so as to comply with either the requirements set out in paragraphs 6.1 and 6.2 or the requirements relating to take-off distance set out in either of those manuals.
Note: The data contained in some manufacturers’ data manuals is unfactored and makes no allowance for degraded aircraft performance. Where there is a considerable difference between the data in a manufacturer’s data manual and the data in the flight manual for the aeroplane then the manufacturer’s data should be treated with caution.


It is quite legal to operate using unfactored data from the manufacturer.

Unfortunately , most of the manufacturers data I have seen only allows for dry, paved, level runways. Some data does allow for adding 10% etc for various conditions. Trying to factor in all allowances for surface, slope etc., Voodoo science.


Passing the point of commitment on an slightly uphill, wet, grass runway in a 40 year old airframe uttering, I think I can, I think I can ... Coroners Court anyone?

.

[MakeItHappenCaptain]

And don't forget to mention that once you get a CASA approval to use the factory manual, you are required to remove all copies of the old CASA charts too. Who gets the blame then?:confused:

[Two_dogs]

You don't need CAsA approval. The approval is CAO 20.7.4

[duncan_g]

My school required the addition of 15% safety factor as an ops manual requirement.

[john_tullamarine]

It is quite legal to operate using unfactored data from the manufacturer

Perhaps .. but possibly not a good risk management approach to things ..

[Two_dogs]

John, That's what I said.
Trying to factor in all allowances for surface, slope etc., Voodoo science.

Passing the point of commitment on an slightly uphill, wet, grass runway in a 40 year old airframe uttering, I think I can, I think I can ... Coroners Court anyone?

[djpil]

.... sets out the take-off distance required for that aeroplane ...The manufacturer's data (not FAA approved) for my airplane does not use the word "required", just mentions "takeoff distance" along with the note "represents maximum airplane capability at speeds shown and requires aircraft in good operating condition and a proficient pilot."
At speeds shown? "Speed at 50 feet - 50 kts IAS". cf stall speed 47 kts?
(not all airplanes are certified to a recent version of FAR 23)
No thanks, not for me.

CASA says that the old "P" charts are no longer approved data so I would need to take responsibility for them. I have a serious query so asked for the data to support them but nil response.

[john_tullamarine]

djpil and I, both having designed a few of the old charts (at least, I think he has .. if not, he certainly would have no trouble so doing) can suggest that they are conservative without being unrealistically so. As he observes, the same cannot be said, necessarily, about some of the various OEM data which is not FAA-approved.

For those who are not aware, the old DCA style charts are based on some internal tech memos which are probably not available generally (I have some copies tucked away somewhere in the filing cabinets). The earlier were quite simple (Ron S and Ian C as I recall) and the later one (intended for light turboprops and done by John F) somewhat more involved.

[HarleyD]

Re performance charts:

The procedures used to determine landing and take off distances are of a wide disparity and are somewhat problematic to use as an apples to apples comparison between types.

Late certification standards, FAR 23 at recent amendment status, define procedures and make the manufacturers figures more believable and not dependant on extremely accurate adherence to procedures and split second timing.

Avarage ability is the standard and delays are factored into the procedures. Procedures are broken down into individual actions with time intervals between and only 'moderate' braking is permitted. There must be no requirements for excessive force or exceptional piloting skills. This results in reasonably achievable numbers, and not absolute ones. A practiced pilot should be easily able to meet or do better than published figures in this instance, eeven using the exact same speeds and proceedures as the manufacturers pilots. All speeds are factored from stall speeds obtained in a conservative configuration (MTOW and FWD COG) so further margins apply. Likewise the requirement to define Vr for Part 23 aircraft now applies. Conservative expansion of data now also provides large penalties for extrapolated PH

This is somewhat arbitraray if course, as many older performance charts and tables included numbers obtained for the sole purpose of sales and marketing and represented the absolute max achievable peformance. These figures are difficult to readily replicate by pilots of 'average' ability. They are rubbery figures and comparing them to new GAMA charts is an academic exercise.


AFM/POH supplements for STC devices have not traditionally been subject to the same level of scrutiny even as lower standards of older certification basis' so this can also muddy the waters.

A good guide for 'average' pilots is that recently certified aircraft will likely have reasonably achievable figures. These charts are very representative and prudent factoring is not normally needed. Older aircraft designs will certainly include lower margins

HD

[MakeItHappenCaptain]

You don't need CAsA approval. The approval is CAO 20.7.4


Form 598. You do need to identify which manual you are using.


Passing the point of commitment on an slightly uphill, wet, grass runway in a 40 year old airframe uttering, I think I can, I think I can ... Coroners Court anyone?


Yeah, but there's a difference between using common sense and blindly applying unnecessarily big safety factors to every single situation because your flying school doesn't employ instructors who know any diferent.

Kinda like going full tanks everywhere because that's what you did at XYZ's Flight Academy or applying a 1.25 factor to a caravan going off a level dirt strip because you haven't read the rules properly. Surely Cessna haven't screwed it up that badly?