This documentation presents an example of a VOR/DME approach performed with a Boeing 737 at DABB on the runway 18.
This type of approach is a non-precision approach due to the fact that only lateral guidance is provided using a VOR.
The pilot-in-command is in charge of the descent.
In this document we will show you how to do the VOR/DME approach without using your FMC and LNAV function but according to the B737 SOP It's recommended to use the LNAV fonction while performing a Non ILS Approach like the VOR/DME .
VOR (VHF omnidirectional radio range) is a radio beam transmitter that provides a VHF radio signal on the air in order to determine an aircraft’s position and stay on course by receiving radio signals transmitted from a ground beacon.
Each VOR approach, during instrument flight rules (IFR) operations, is published on an instrument
approach procedure chart named IAC chart.
This chart includes:
Before the approach phase you must brief your approach and set up all the aircraft parameters to do your approach .
Prepare your course as the B737 is a CAT C aircraft (VAPP between 121-140kt) so our course will be 029 to follow the outbound radial 029 of ANB until 10.5
At ANB VOR we must be at 4600ft then we continue our descent to 2400ft until 10.5NM DME ANB (2400ft because we take the nearest 100ft of the altitude)
The MDA for our approach is 410ft so during our approach if we don't see the runway we will maintain 410ft
For example in the chart of our approach we can see that the glide path angle is 3.00° to know exactly
the V/S that we must follow we use the following mathematical formula:
V/S (FPM) = Glide path angle (°) * GS(kt)
If our GS is 150KT
V/S=3*150=450FPM (feet per minute)