[For full details of the techniques used refer to: Practical Flying Guide 1 - Visual Navigation.]
Like previous lessons, the instructor will have given the student a route to plan. The student should plan three legs, each approximately 20 minutes flight time. However, the third leg should not go back to the home airfield, but to another waypoint. The third leg will be used to plan and execute an en-route diversion back to the home airfield.
On the day of the flight the student should have completed planning for the route and carried out all the pre-flight actions, including NOTAMs and weather assessment. Again, some instructor input and advice may well be needed. Make sure the student has marked the wind on the map including the maximum drift.
A thorough briefing will be required before this flight lesson is conducted, particularly the techniques to be used for weather avoidance and the en-route diversion, as well as the threats or errors which could require one.
A structured and time-based approach to navigating, distributing tasks and managing workload to ensure other important tasks are being attended to, such as lookout, radio calls, cruise checks and weather assessment.
Regular cruise checks, leaning of the mixture, as well as fuel monitoring and recording.
Workload management, using time frames, resulting in a thorough lookout and situational awareness being maintained.
Starting prior to take-off the student briefs the aerodrome departure and heading to the SP. After take-off they should climb to the SP and set course on the first leg. The student should be capable of navigating to the first Turning Point (TP) with the minimum of instructor input using the techniques taught in the previous lessons.
On arriving at the first TP, the student should be able to identify the TP and set course along the next leg.
Once the aircraft is successfully established on the second leg, take control and teach the weather avoidance technique which uses a dogleg to leave track, avoid the weather, parallel track if appropriate, and then return to track. If possible, try to regain track before the next fix, so that the success of the dogleg technique is confirmed. After the fix, allow the student to practise the weather avoidance method, returning to track before the next TP.
If an actual weather avoidance is not necessary, rather than just simulating a rain shower try to organise the route where there may be some isolated high ground. Then simulate a low cloud base. This will result in a dogleg around the high ground and being able to literally see how it works. This does depend on the local terrain and thinking ahead when the route for planning is initially given to the student.
Once past the second TP, take control and teach how to plan and perform a diversion to an alternative destination. Start by nominating the diversion destination (in this case the home airfield) and then a suitable SP, either a ground feature or a point along the time scale (e.g. in 3 minutes time). Then teach them to free hand a line on the chart from the SP to the destination, and then to estimate the True track, convert to Magnetic and calculate a heading derived from the maximum drift already marked on the map. Position to be overhead the SP and on the new heading. Note the time and emphasise the gross error check and the WHAT check, as the chance of making a mistake in airborne planning is increased. The student should then draw in 6-minute markers and estimate ETA. They can then choose suitable fixes noting the time to the next fix. Once this is complete, the map can be put away, hand control back to the student and from this point onwards the techniques to navigate this leg are no different to any other leg previously flown. Once under way, other tasks can be accomplished in the same managed way as previously taught, and would include a review of any airspace ahead, fuel remaining, fuel required and MSA for the leg.
The student should be able to manage the arrival and entry to the circuit. Consider practicing a different type of approach and landing, such as a flapless, short-field or glide approach.