Sunday, 14 September 2008

PPL Ex 18 (xvii): Navigation Planning: Example: EGBD - EGTK - (Part 4: The Navigation Plan - Pilot's Log - PLOG + Load Sheet)

Two good aviation sites are here and here.

(Click on an image to ENLARGE.)
Let's continue with the EGBD - EGTK - EGBD practise flight. The UK Low-Level Spot Wind Chart (Form 214) has been downloaded from and the winds appropriate to our flight applied to the pilot log.
Having interpolated the wind and temperature information from the Met Office Chart (F214) it is now possible to calculate True Airspeed (TAS), True Headings (TRU HDG) and Ground Speeds (GND SPD). The TAS is calculated from the AIR SPEED window on the airspeed side of the flight computer. At 2,600ft the temperature is +08-deg C (average over the route). See (Illustration A.). The IAS will be 100 kts (See TAS in the Airplane Flight Manual (AFM) or the Pilots Operating Handbook (POH)).

On the Flight Computer: Opposite 100 on the inner scale, read 103.5 knots on the outer scale. See (Illustration B). This is the TAS, and it concurs with the AFM (see both pictures below). The Ground Speed information allows the Time calculations (TIME MINS) and also, therefore, the Fuel Required - from the AFM or POH the fuel consumption is calculated as 6.6 Imp. Galls. per Hour. The Magnetic Headings (MAG HDG) are calculated by applying the chart VARIATION (VAR).

(Illustraion A above.)
Note: Do not confuse a meridian of Longitude for the degrees of variation. E.g. 3 deg W Longitude, but 3.5 deg W of Variation.

By applying the DEVIATION (DEV) the Compass Headings (COMP HDG) are calculated. (Note: The DEVIATION is not normally known at this stage of the planning process. The aircraft will have a Compass Deviation Card near the compass. This will give a For (Magnetic Heading) and Steer (Compass Heading) table.)
(Illustration B.)

Deviation Card >>>>>>>>>>

All the information is now available to complete the navigation plan or Pilot's Log - sometimes known as the PLOG.

On this PLOG the Estimated Remaining Fuel after holding for 45 minutes and having used all of the 10% Contingency, is 3.4 Imp. Galls. This equates to 31 minutes at 6.6 Imp. Galls. per Hour.

Note 1: The legs from EGBD to CB VRP and from EGTK to Charlbury VRP and from CB VRP to EGBD are VARIABLE in terms of TAS and TRU TRK. This is for two reasons: 1.) The aircraft will be climbing or desecending, and 2.) The departure runways are not yet established so the initial/final track is not fixed.

Note 2: No allowance has been made for the descent into EGTK because: 1.) the leg from BITTESWELL VRP is relatively long and 2.) to keep the PLOG reasonably straight forward.

Corrrection: In the above Pilot Log the Contingency should be 1.2 not 1.8.

Finally, it is necessary to complete the Weight and Balance Table. See below:

Note: It is a good idea to start the whole process of flight planning with a calculation of how much FUEL it is possible to load. Therefore, the Passenger and Baggage weights must be estimated accurately. The sum of these values, added to the Basic Empty Weight (Mass), are subtracted from the Maximum Allowable Take-off Weight (Mass) (MTW) for the Runway, Density Altitude & Wind Velocity values. This will be the maximum weight of fuel possible. The Weight and Balance Table also allows the calculation to be made in order to ensure that the aircraft is correctly loaded within the Centre Of Gravity Moment Envelope. See below:

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