Important calculations

On this page you will find important tables, which greatly simplify the correct execution of the flight. There are Flight simulator simplified procedures, but they are very helpful. This is often the case when flying without the help of the FMC. Especially with Online flights, if the requirements of the ATC must be met and you can only can estimate when, for example, a descent to a lower flight level must be initiated to fly over a VOR at a certain altitude. Furthermore you will find calculation possibilities for the duration of a climb or and the distance that is covered during the descent; and some more other...

How long does a turn take?

important: bankangle 25 degrees, maximum value during passenger flight
Rule of thumb: TAS (true air speed) x 0,83 = Flight time for a 360° turn
e.g. 250 kts x 0,83 = 208 Sec. for 360°, 104 Sec. for 180° etc.
Calculation for any curve: TAS x 0,83 / 360 = T (Flight time for 1° change of direction)
e.g. change of direction about 110 degree, Speed 250 kts: 110 x T (0,6) = 66 Sec.

When do I have to turn to change direction?

The decisive point here is the angle of refraction (AOL/angle of lead), i.e. by how many degrees does the new course deviate from the course currently flown, e.g. from a BEFORE.
Of course, the flight speed and altitude would also have to be included in the calculations.
In order to be able to omit all the arithmetic, here are simple values for the curve:
AOL ca. 30° = 2 NM
AOL ca. 60° = 3 - 4 NM
AOL ca. 90° = 5 - 6 NM
AOL ca. 120° = 7 - 8 NM

What is the rate of climb when climbing (ROC/rate of climb)?

Basic data for Twinjets ( B737,757,767, Airbus 3x0, MD 8x)
After rotation, pitch angle (pitch) of 20 degrees
From 1500ft AGL Pitch reduce to 10 degrees and keep stubborn
When the AP is activated,
up to FL 100 rate of climb 2200ft/min
up to FL 200 rate of climb 1800ft/min
up to FL 250 rate of climb 1500ft/min
up to FL 300 rate of climb 1000ft/min
above about 500ft/min, partly less

When does the descent begin?

Rule of thumb: Altitude difference / 300 = Distance in NM in which the descent must be started.
This point is called TOD (Top of Descent).
To this distance specification one adds 10 NM as reserve.

How big should the Rule sink rate be (ROD/Rate of Descent)?

Standard sink rate for the Flusi 2500ft/min, partly from very high heights also 3000ft/min
At lower altitudes 1800ft/min.
The angle of attack (AOA) should ideally be 2,5 degrees during descent.

Sink rate on the ILS

The sink rate depends on the inclination of the glide path.
The standard inclination is 3 degrees worldwide.
e.g. Speed 160 kts x 5 = 800, Sink rate is 800ft/min

Angle of inclination of the glide path Multiplier
1,5 x Airspeed
3 x Airspeed
3° (default) 5 x Airspeed
7 x Airspeed
8 x Airspeed
10 x Airspeed

When is a climb or descent initiated?

Rule of thumb: Height for recovery = Vertical Speed times 0,2
e.g. Climb rate 2000ft/min; 2000 x 0,2 = 400.
So divert about 400ft before reaching the new altitude.

What airspeed during descent?

Default values:
to FL200 ca. 300 kts
to FL120 ca. 270 kts
to FL110 ca. 260 kts
below 10.000ft max. 250 kts

What airspeed on approach to the airport?

Approach to the ILS not more than 180 kts (even if 210 kts are allowed)
Approach with 210 - 200 kts, flaps extended to 5 degrees, speed is automatically reduced to 180 kts without having to operate the thrust controls.
Then extend the landing gear, speed decreases further.
Cutting the ILS target speed 170 kts, flaps 15 degrees, extend the landing gear.
Speed at Middle Marker 160 kts, flaps 25 degrees
Speed after the MM, but before the Inner Marker 150 kts, flaps 30 degrees
Reduce speed at IM to landing speed 140 kts, flaps full.
By the controlled extension of the flaps, the speed is usually reduced automatically to the desired value without the need to operate the thrust lever. (N1 approx. 55 %)
The mentioned speed and flap values are intended as a general guide.
High-end aircraft such as the PSS... PIC, DF etc. allow more accurate values due to the exact flight data acquisition.

Flight time data, or... How long does the climb / descent take?

Climb time (Tclimb) = Flight altitude (ALT) / Climb rate (ROC)
e.g. 26000 feet / 1800 feet per minute = 14,5 minutes, i.e.: the climb to the height of 26000 feet takes about 15 minutes.
The 26000 feet in our example refer to the departure from an airport at sea level.
The calculation is always based on the actual height difference.
descent time (Tdesc) = height difference / descent rate (ROD)

What distance do you cover in this time?

Distance (Dclimb) = Speed GS * Tclimb = 325 NM per hr * 14,5 min/60 = 78 NMd.
i.e. a speed of 325 kts is assumed here. During the climb to the altitude of 26000 feet a distance of 78 NM is covered.
The calculation of the descent time (Tdesc), as well as the flight distance during the descent (Ddesc) is analogous to the climb or distance.

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