- 1 Introduction
- 2 Maximum operating speed (VMO)
- 3 Speed reduction and regulation
- 4 Approach speed
- 5 Bank angle
- 6 Performance table
- 7 See also
- 8 Reference
- 9 Author
Each type of aircraft has its own characteristics, which determine their category in the approach.
The main points of difference will be found at:
- Maximum Operation Speed
- Approach Speed
- Minimum Clean Speed
- Final Approach Speed
- Minimum Approach Speed
- Rate of Climb/Descent
Maximum operating speed (VMO)
When the VMO is exceeded the aircraft can be damaged:
- Excessive mechanical constraints on the aircraft structure leading to permanent deformations
- Excessive mechanical constraints on the engine air inlets
- Deformation of bearing structures
- Shock waves leading to shakes, loss of bearing capacity and bad manoeuvrability
- Unusual heating
Together with the VMO, other characteristic speeds are defined for some airplanes:
- VNO: Normal Operating speed
- VNE: Never Exceed speed
In some anemometers the VNE is indicated with a red line.
In some anemometers the speed range above VNO and below VMO is indicated with a yellow arc.
Speed reduction and regulation
The speed reduction can be rather long: a reduction from 320 to 220 KIAS requires 10 NM at 10000 ft and 7 NM at 5000 ft.
Spoilers and speed brakes are secondary flight control surfaces that can be deployed manually by the pilot or, under certain circumstances, extend automatically. Speed brakes are purely drag devices while spoilers simultaneously increase drag and reduce lift.
Once the cleared speed is reached he can retract the speed brakes and adjust the thrust to maintain this speed.
- ask the pilot to reduce speed and then perform a descent at reduced speed
- ask the pilot to descend and then proceed with the speed reduction
This speed is different from what is displayed on the ATC radar which is the GS (Ground Speed), equal to the TAS (True Air Speed) corrected by the wind drift.
It is completely useless for a controller to use the IAS as a regulation means when the aircraft are separated by more than 4000 ft.
For a given IAS and a given flight level, the TAS varies only little within a range of ± 2000ft around this level, but TAS can have significant difference when the altitude difference is more than 4000ft even if both aircraft will use the same IAS.
Then, a controller will use a speed regulation in order to maintain current regulation when the altitudes between all aircraft in the sequence are comparible.
The 220 KIAS speed
The main advantages of this 220KIAS speed are:
- For most aircraft the minimum clean speed (flaps and slats retracted) is lower than or equal to 220 KIAS
- This is the maximum allowed speed of holding circuits below FL140
- The aircraft can easily accelerate if needed since flaps and slats are still retracted
- The aircraft can easily decelerate since most of the times flaps and slats can be extracted immediately without waiting to reach a lower speed
The minimum clean speed
The use of this speed can be useful for the controller in case a deceleration is needed since it does not affect the fuel consumption which increases significantly when flaps are extracted.
High speed on final
Depending on the aircraft, the final approach speed ranges between 110 and 170 KIAS (except general aviation airplanes).
Beyond the FAF/FAP or the OM the controller cannot impose a speed restriction and shall negotiate it with the pilot who is the only responsible of his final approach speed.
The minimum approach speed
It is advised not to impose such a speed restriction before 15 NM from the airfield since it would oblige the aircraft to fly a rather large distance in a configuration close to the stall speed. Moreover, this configuration leads to a significant increase of the fuel consumption.
During a holding circuit at the minimum clean speed or at the published maximum hold speed the bank angle shall not be less than 25°. The bank angle is reduced to 15° when flaps are extracted. This is due to the fact that in this configuration the indicated speed is close to the stall speed and the airplane is generally at rather low altitude.
Nevertheless, the protection volume of a published circuit is designed to take into account several parameters, uncertainties and the different possible joining procedures.
In the table below, some general performances are presented to provide an overall view to the controller:
|Aircraft type (examples)||Maximum Operation Speed (IAS)||Approach Speed (IAS)||Minimum Clean Speed (IAS)||Final Approach Speed (IAS)||Minimum Approach Speed (IAS)||Rate of Climb/Descent (ft/min)|
|General Aviation: BE55 C182 C310 PA31 PA46 TB20||120-220 (Vmo)||80-180||75-100||70-110||60-95||C: 500-1500|
|Turboprop: AT42 BE90 B350 C130 DHC8 E120 F27 F50 S340||180-280 (Vmo)||150-250||120-150||110-140||80-115||C: 1000-2500|
|Private jets: BJ40 C550 FA20 FA50 HS25 LR35 LR45||230-390 (Vmo)||180-280||150-180||120-150||95-125||C: 1500-5000|
|Liners: A310 A320 B717 B737 B757 CRJ7 DC10 IL62 MD80||220-350 (Vmo)||200-280||170-230||120-160||105-145||C: 1000-3500|
|"Heavy" Liners: A330 A340 B747 B777 MD11 A225||230-360 (Vmo)||200-260||210-250||140-170||125-155||C: 1500-3500|
- VID 150259 - Creation
- VID 435695 - Revision and wiki integration
DATE OF SUBMISSION
- 05:46, 14 May 2021
- This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.
- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.