How Should You Fly an Instrument Approach?

A Real Training Scenario

Here's a scenario of a pilot attempting to regain instrument currency in our simulator:

The pilot was receiving radar vectors for an ILS approach and was approximately 25nm away from the airport. He briefed the approach and told ATC that he was ready. ATC instructed him to descend and proceed to a fix that was on the final approach course, and cleared him for the ILS approach.

This was when he noticed that he didn't have the fix set up in the flight plan on his G1000 as he loaded the approach with vectors-to-final. As he scrambled to reload the approach, he started getting "behind the airplane" and forgot to descend to the altitude that ATC assigned for him.

When he eventually caught up with all the tasks, ATC reminded him again to start his descent. He complied and started the descent while extending the landing gear and approach flaps even though he was 20nm from the field.

As he joined the final approach course, he decided to "dive and drive" to every step down altitude published on the chart. This increased his workload as he had to constantly adjust his power settings every time he started a descent and every time he leveled off.

Upon arriving at the decision altitude, he made visual contact with the ALSF-II approach lighting system but seemed unsure as to whether he could continue to descend towards the runway. As a result, he initiated a missed approach procedure. He climbed, cleaned up the flaps and landing gear, and ATC advised him to fly the published missed approach. However, because he never set the missed approach altitude in the altitude preselector, he eventually climbed above the missed approach altitude and caused a traffic conflict with other IFR traffic in the area.

In this short 15 minute approach, we found many areas where he could have done a lot better that would help him stay "ahead of the airplane."

1. When Should I Configure for the Approach?

Every approach that you fly is different in some way, whether it is the type of approach, weather conditions, or traffic density. It is important to follow your personal techniques but also adjust them accordingly for each individual approach.

For most scenarios, I would advise planning to be in a clean configuration when being vectored by ATC to join the final approach course. This helps ATC plan out how to vector all of their arrival traffic while ensuring proper spacing and efficiency.

After you become established on the final approach course and approximately 2-3nm prior to the final approach fix, extend the appropriate approach flaps and extend the landing gear (if applicable). The extra drag will also aid you in slowing down to your approach speed.

Maintain this configuration until you have the runway environment in sight and are in a position to execute a normal approach to landing. Slowing down preemptively during the final approach phase not only makes it more difficult to achieve a stabilized approach, other factors such as descent rates and the time needed to travel from the FAF to MAP will also change, resulting in increased workload in a critical phase of flight.

2. How to Be Prepared for a Missed Approach

Flying an airplane equipped with autopilot is a good way to help mitigate risk by avoiding task and workload saturation. However, a pilot can only effectively manage risk by properly programming the flight management system and selecting the appropriate autopilot modes for the phase of flight.

When crossing the final approach fix on an instrument approach, a good habit to develop is to set the missed approach altitude in the altitude preselector. As you arrive at your decision altitude or missed approach point and need to conduct a missed approach, pressing the TO/GA button will activate the missed approach segment of the flight plan and the autopilot will start a climb towards the altitude set in the altitude preselector.

If the altitude in the preselector is not the appropriate missed approach altitude, the autopilot will be restricted by that erroneous altitude, resulting in an undesired flight path. This risk can be easily mitigated by simply developing the habit of setting the missed approach altitude whenever you cross the final approach fix.

3. Vectors-to-Final vs Selecting an IAF

In an ideal world, every instrument approach you do, ATC will vector you onto the final approach course. However, that is not always the case.

When programming the instrument approach into the flight management system, ALWAYS load it from an initial approach fix (IAF) that is appropriate for your inbound direction. This is because ATC could instruct you to fly direct to any charted fix, which would not be present in your flight plan if you loaded the approach with vectors-to-final.

In that situation, you would likely have to reload the whole approach just to comply with those ATC instructions, resulting in unnecessary workload in this critical phase of flight.

The better alternative is to load it from an IAF, and then activate vectors-to-final when appropriate. This also improves your situational awareness as you can easily estimate your distance away from the airport or your final approach fix.

4. How Low Can You Go?

When flying an instrument approach in hard IMC, it's important to know exactly how low you are authorized to descend to. Typically this is fairly easy information to extract from the approach plate during your briefing, but do you know what you are looking for when you approach minimums?

It's important to review and know the list of things that qualify as runway environment as per 14 CFR 91.175 so you can make an informed decision of whether to continue the approach or initiate the missed approach procedure.

Moreover, how many of you do the math to calculate what 100 ft above the touchdown zone elevation is? Why is this important? Well, if you approach minimums and you only have the approach lighting system in sight, you are legally authorized to descend to 100 ft above touchdown zone elevation, which by then you must make visual contact with the runway environment before continuing to land.

This makes a huge difference especially on non-precision approaches that have fairly high minimums.

5. Should You "Dive and Drive"?

When conducting an approach with multiple step down fixes, a method often used is known as "dive and drive." This is when the pilot descends to the step down altitude as soon as possible and levels off at that altitude until crossing the next fix.

While it is 100% safe to conduct an approach using this method, I personally prefer to try to intercept the glide slope or glide path as far out as possible and fly a constant vertical descent path, while still ensuring that I abide by the charted altitude restrictions.

This minimizes pilot workload and allows the airplane to easily perform a stabilized descent with relatively little power or thrust changes.

Frequently Asked Questions