Page 2-13
Pilot’s Operating Manual
Revision A1: Nov, 2002
Sub-section 2
PREFLIGHT
Hawker 800XP Pro Line 21
Section IV - FLIGHT PLANNING DATA
Part 3A - FLIGHT PLAN DISTANCES
If there is a headwind or tailwind component, then an Equivalent Still Air Distance (ESAD) must be
estimated for the sector from the departure airfield to the destination, and for diversion from the
destination to the alternate airfield.
An approximate still air speed is first determined and then knowing the actual distance, wind and mean
speed, the equivalent distances may be obtained from the (EQUIVALENT STILL AIR DISTANCE) tables
in this section.
Equivalent Sector Distance
Obtain an approximate still air Sector time from the tables for an appropriate procedure (High Speed,
Intermediate or, Long Range) assuming a reserve fuel of say, 2000 lb to give an approximate arrival
weight.
For this example we shall use the High Speed Procedure data for ISA conditions (an acceptable
approximation to ISA+5° C) and an approximate arrival weight of 16,900 lb + 2000 lb = 18,900 lb.
This gives a Sector time for 1900 nm of about
270 minutes at the highest achievable cruise altitude of
39,000 ft.
Mean Sector speed is thus: 60 x 1900 =
422 kt
270
and the ESAD from this section is
1814 nm by interpolation between the 400 kt and 450 kt tables at a
Sector distance of 1900 nm and a tailwind of 20 kt.
Equivalent Diversion Distance
The ESAD for the diversion is obtained in a similar way using Zero Fuel Weight plus approach and
landing fuel as the arrival weight.
In this case we shall choose an altitude of 15,000 ft on the basis of the approximate rule of assuming
10,000 ft altitude per 80 nm of diversion distance.
This makes sure that cruise distance will be at least half the total distance.
(A lower diversion fuel could be achieved by assuming climb to a higher altitude and a shorter cruise)
From this section (Diversion Time and Fuel) for an arrival weight of 17,000 lb and 15,000 ft cruise
altitude, we see that time is
28 minutes for a diversion distance of 120 nm.
Mean still air speed = 60 x 120 =
257 kt
28
If we use the conservative rule of assuming 50% actual tailwind component or 150% headwind
component, then ground speed will be 30 kt less than this.
ESAD
= distance x mean still air speed
ground speed
= 120 x 257
227
=
136 nm
