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Regulation: Minimum height for turn after takeoff??
Good Day All,
What's the minimum height (by regulation) at which we can start a turn after takeoff ? Ex: Out of an airport where there are no SID. "XXX You are clear for takeoff rwy 36, when airborne turn right HDG 090° climb 6000 Ft, report maintaining" (There are no company procedure, no obstacles, no specific a/c perfo and no airmanship consideration) Most of the time, when I ask to a colleague the answer is 400 Ft. (But I'm afraid their answers are: 1) Preconditioned by my company procedure, and 2) The 400 Ft climb for SID's design criteria (DOC 8168) In the back of my head, I have a much much much lower value.... Would this height be related to certain conditions: VMC/IMC - VFR/IFR - (Class A/B or Large/Small) aircraft - General/Commercial Ops ? Thanks, |
With this departure you are still on IFR flight plan and it's an IFR procedure, so 400ft seems reasonable.
No benefit of turning earlier (especially versus the risks), and in case of flat terrain and no obstacles, no issue that would require flying straight for longer. And depending on the aircraft's AFDS configuration, you might not be able to change the AFDS roll mode below 400ft as well. Keep it simple. |
Hi! My answer would be too significantly lower. I’d say no turns at all below 50ft or half the wingspan, then max bank of 15° up to 400ft then max 25° up to 1500ft. This might change after after approval for banks 20° between 200-400ft then 30°. But the min height for turns I’d say too 50ft or half the wingspan. |
But I’d say too, for turning departures no turns should be done below 394ft |
Turns can be commenced (beyond 5 degrees from centreline) as follows:
From FAR: Height (above Departure End of Runway - ft) v Maximum Bank Angle (degrees): No turns below 50' 50' < h < 100' maximum bank 15 degrees 100' > h > 400' maximum bank 20 degrees h > 400' maximum bank 25 degrees So when flying an average jet performance aircraft, with automation standard bank angle of 25 degrees (or 30 in LNAV) turning at or above 400' makes perfect sense |
Would you mind posting song and verse of the respective regulations? |
no airmanship consideration |
FAA AIM 5-2-7 para b.1:
1. Unless specified otherwise, required obstacle clearance for all departures, including diverse, is based on the pilot crossing the departure end of the runway at least 35 feet above the departure end of runway elevation, climbing to 400 feet above the departure end of runway elevation before making the initial turn, and maintaining a minimum climb gradient of 200 feet per nautical mile (FPNM), unless required to level off by a crossing restriction, until the minimum IFR altitude. A greater climb gradient may be specified in the DP to clear obstacles or to achieve an ATC crossing restriction. http://www.faraim.org/aim/aim-4-03-14-302.html 8260.43F Departure Procedure (DP) Program DPs must not require a turn prior to reaching 400 feet above the departure end of runway (DER) elevation. See Order 8260.3 and Order 8260.58, United States Standard for Performance Based Navigation (PBN) Instrument Procedure Design, when a turn is required within two nautical miles (NM) of departure end runway (DER). No turns are allowed in the ICA (Initial Climb Area) 400' above DER. |
In the UK it’s 500’ before turning for an omnidirectional departure. |
EGPFlyer provides a verse of regulation that applies in the UK and most likely to UK registered aeroplanes globally, within the scope of the question.
Smythe, by all accounts, quotes a rule for the design of departure procedures. While it exists for a good reason, it is outside the scope of the OP's query. Useful debate on both sides but perhaps also worthwhile keeping the two baskets separate. Directly from the AIM link provided: All DPs provide the pilot with a way to depart the airport and transition to the en route structure safely. Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available. The following paragraphs will provide an overview of the DP program, why DPs are developed, what criteria are used, where to find them, how they are to be flown,... My point being, the rules how to fly a DP only apply if the pilot needs or chooses to fly one. |
I would not commence a turn myself until a minimum of 500' in case of an EFATO.
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Lanzarote GCRR rwy 03? Survival aspects may dictate otherwise. |
The AFDS roll mode has nothing to do with it. 400ft, as specified in the AIM (FAA rules), or as indicated otherwise. My company used to want us to start turning at 100ft leaving LGA. Not sure if it's still so.
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My company used to want us to start turning at 100ft leaving LGA. Not sure if it's still so. |
Performance wise - EASA CAT.POL.A.210 Track changes shall not be allowed up to the point at which the net take-off flight path has achieved a height equal to one half the wingspan but not less than 50 ft above the elevation of the end of the TORA. Thereafter, up to a height of 400 ft it is assumed that the aeroplane is banked by no more than 15°. Above 400 ft height bank angles greater than 15°, but not more than 25° may be scheduled. Design wise - PANS-OPS 8168 I-3-2-2 When a departure route requires a turn of more than 15°, it is called a turning departure. Straight flight is assumed until reaching an altitude/height of at least 120 m (394 ft), or 90 m (295 ft) for helicopters. Procedures normally cater for turns at a point 600 m from the beginning of the runway. However, in some cases turns may not be initiated before the DER (or a specified point), and this information will be noted on the departure chart. No provision is made in this document for turning departures requiring a turn below 120 m (394 ft) (90 m (295 ft) for helicopters) above the elevation of the DER. |
There are specifically designed turning departures and the obstacle clearance surface analysis reflects this. The minimum altitudes are a blank worst case scenario so as to not have to consider each aircraft turn performance for obstacle clearance.
That being said, RNP DEP are custom, and the obstacle clearance surfaces, coupled with turn degradation performance are considered. After you calculate the performance in a turn, then you must consider the bank limitation of each aircraft type. Many aircraft are bank limited below 400 feet. I think the 747/777 are limited to 8 degrees below 1000 feet, and 3 degrees below 500 feet? |
The part 77 obstacle clearance surfaces do not support a turn below 400 feet.
There are specifically designed turning departures and the obstacle clearance surface analysis reflects this. In general, for AEO departures, the surveys are for a straight ahead takeoff. Some runways will have a low level turn AEO for terrain - eg YMHB R30, for many years, had a right hand turn over the bay to avoid high terrain to the northwest. If an OEI departure requires a turn for terrain, this generally will be a per-Type requirement and the terrain analysis and splay development is a problem belonging to the operator/crew. The aerodrome owner is only going to run the minimum survey (costs) required by regulations. Bank limits will be per AFM data and/or special procedures negotiated with the Regulator and based on engineering analysis. |
Originally Posted by Smythe
(Post 10433537)
The part 77 obstacle clearance surfaces do not support a turn below 400 feet.
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It is also worth thinking about spiral stability. If the rudder trim is not perfectly centred (unlikely to be the case immediately after T/O), and if there is a slight asymmetry of thrust, the aircraft could be spirally stable in one direction and spirally unstable in the other. Lateral trim can also affect spiral stability. It is difficult to find the zero setting while still on the ground. The spiral stability of most jet transports is substantially neutral. However, if your aircraft is not perfectly spirally stable, any relaxation of attention to the bank angle could allow it to bank further than you want. I would recommend waiting until 500ft before starting a turn after take-off.
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Originally Posted by FlightDetent
(Post 10433167)
My point being, the rules how to fly a DP only apply if the pilot needs or chooses to fly one.
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