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Do you really have the available runway distance published?

August 14, 2023/in Tips and technique/by Eric Radtke

How do you start a jet engine?

August 11, 2023/in Tips and technique/by Eric Radtke

Do you really have the available runway distance published?

August 14, 2023/in Tips and technique/by Eric Radtke

How do you start a jet engine?

August 11, 2023/in Tips and technique/by Eric Radtke

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Do you really have the available runway distance published?

August 14, 2023/in Tips and technique/by Eric Radtke

Declared distances for the Naples Municipal Airport located in the Chart Supplement.

In the Chart Supplement entry for many airports, especially those frequented by jet aircraft, you’ll see a collection of runway distance information that may differ from the runway length information published on the airport diagram. These declared distances represent the maximum distances available and suitable for meeting takeoff, rejected takeoff, and landing distance performance requirements. The airport owner provides the declared distances for inclusion in the Airport Master Record and the Chart Supplement for each operational runway.

While the declared distances formally apply to the certification and operation of turbine aircraft, it is valuable information to all pilots.

Declared distance information includes:

TORA (Takeoff Run Available);
TODA (Takeoff Distance Available);
ASDA (Accelerate Stop Distance Available);
LDA (Landing Distance Available).

For runways without published declared distances, the declared distances are equal to the physical length of the runway unless there is a displaced threshold which would shorten the distance available for landing by the length of the displaced threshold.

Declared distances can also increase runway use. Declared distances that use a clearway or stopway can increase TODA or ASDA can provide turbine aircraft additional performance capability and increased maximum allowable takeoff weights.

TORA (TakeOff Run Available)

The TORA is the length of runway available for takeoff run requirements. When the full runway beyond the start of takeoff is available for the takeoff run, the departure end of the TORA is located at the departure end of the runway. A reduced TORA can be used to mitigate incompatible land uses in the departure runway protection zone (RPZ) or to mitigate environmental impacts.

Example of a shortened TORA.

TODA (TakeOff Distance Available)

The TODA is equal to the TORA plus the length of any remaining runway or clearway beyond the departure end of the TORA available for satisfying takeoff distance requirements. A clearway is a rectangular area beyond the end of a runway cleared or suitable for use in lieu of a runway to satisfy takeoff distance requirements; however, any portion of the runway extending into the clearway cannot be used for takeoff run calculations.

Example of a standard TODA at the departure end of the runway.

Example of an extended TODA.

ASDA (Accelerate Stop Distance Available)

The ASDA is the length of runway plus stopway available for satisfying accelerate-stop distance requirements for a rejected takeoff. A stopway is an area beyond the takeoff runway which is able to support the airplane during an aborted takeoff without causing structural damage. A stopway also has to be designated by the airport for use.

LDA (Landing Distance Available)

The LDA is the length of runway available for satisfying landing distance requirements. The LDA begins at the threshold. A stopway cannot be part of the LDA.

Example of ASDA extending beyond the LDA.

How do you start a jet engine?

August 11, 2023/in Tips and technique/by Eric Radtke

A typical jet engine consists of an intake or fan section that accelerates air like a propeller. While a lot of the accelerated air bypasses the core of the engine, some of the accelerated air enters the compressor section of the engine where it is compressed or squeezed by blades spinning at a high rate of speed.

After entering the combustion chamber, the compressed air is then sprayed with fuel and ignited by igniter plugs. The expanding gases are directed reward to the turbine section of the engine. The spinning turbines extract enough energy to, in turn, drive the compressor section of the engine and also power various engine accessories. The combination of primary exhaust from the combustion process and the bypassed air routed around the engine from the fan section, create the total propulsion.

Pratt & Whitney JT15D-4B Turbofan Engine

While the basics of jet engine operation are relatively simple, just how do you start the engine to accelerate a large amount of air to get the process moving?

Smaller jet engines are started using electrical power, either from a battery or an external power unit. Upon initiating the start, generally with the push of a button, the battery powers the starter motor which begins rotating the engine just like a piston-powered airplane or your car. Once the engine rotation reaches a minimum speed, ignition is introduced to begin the combustion process. As the engine continues to accelerate, the start sequence is terminated.

Larger jet engines require a dedicated source of air to initiate engine rotation (battery power is not enough) which is generally provided by an auxiliary power unit (APU). Certain ground support equipment (huffer cart) can also provide the necessary air for engine start in the case of an inoperative APU. The APU is a smaller turbine engine that is started using a traditional battery start as described above. Once the APU is up and running, when the main engine start sequence is initiated, air is extracted from the APU to drive an air turbine starter to rotate the engine and begin the start sequence.

Watch the electric engine start of a Pratt & Whitney, JT15D-4B turbofan engine on a Cessna Citation.

Half Sized Blog Element (Single Author Style)

Half Sized Blog Element (Multi Author Style)

Do you really have the available runway distance published?

How do you start a jet engine?

Do you really have the available runway distance published?

How do you start a jet engine?

Full Sized Blog Element (Big Preview Pic)

Do you really have the available runway distance published?

How do you start a jet engine?

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