IFR Lost Comm Procedures § 91.185

What to do if you lose ATC communication on an IFR flight?

When was the last time you experienced a two-way-radio communication failure? After our instrument rating check-ride, we do not think about this topic very often. In today’s airplanes, it is getting rarer to experience any avionics failure. More likely than not, your aircraft still has multiple radios and various sources of electrical power. If the alternator fails, you have a battery; some airplanes even have two batteries. So the chances of having IFR lost communication are slim. But this does not mean it cannot happen.

This article will review the rules and regulations involved in IFR lost communication. We will also explore what to expect and what you should do if you encounter this situation on a check-ride or real life. One of the easiest ways to learn this topic is to associate it with real-life situations. We will use a simulation flight from KTMB to KTPA. Here, we will discuss possible loss communications scenarios in each phase of the flight and the use of the proper rules and regulations to navigate it in these circumstances. Let’s begin!

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Have you ever flown an IFR flight plan in Instrument Meteorological Conditions (IMC) from takeoff to landing?

• § 91.185 IFR operations: Two-way radio communications failure.
  • b) VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable.

Easy right.? But a lot of people forget the basics. These are the steps to follow if you have a radio failure in an IFR flight plan during VMC.

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Now let’s imagine the worst possible lost comm scenario. You have a flight from KTMB to KTPA in full IMC. Here, we will use section C of § 91.185 IFR lost comm and AIM 6-4-1 to explain each part with possible situations that can be encountered in different phases of the flight. Let’s start!

• § 91.185 IFR operations: Two-way radio communications failure.
  • c) IFR conditions. If the failure occurs in IFR conditions, or if VFR procedures cannot be complied with, each pilot shall continue the flight according to the following:
    • Route – ( An easy way to remember this is the acronym AVEF )
      • Assigned – By the route assigned in the last ATC clearance received
      • Vectored – If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance.
      • Expected – In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance.
      • Filed – In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
    • Altitude. – At the highest of the following altitudes or flight levels for the route segment being flown
      • An easy way to remember this is the acronym MEA
        • Minimum IFR altitude – The minimum altitude for IFR operations
        • Expected – The altitude or flight level ATC has advised may be expected in a further clearance.
        • Assigned- The altitude or flight level assigned in the last ATC clearance received;
    • Leave clearance limit.
      • Is the clearance limit a fix where the approach begins?
        • Yes
          • Start descent and approach as close as possible to the EFC time if one has been received, or if one has not been received, as close as possible to the ETA from the filed or amended ETE
        • No
          • Leave clearance limit at the EFC time or upon arrival over the clearance limit. Proceed to a fix from which an approach begins and commence descent and approach as close as possible to the ETA as calculated from the filed or amended ETE.

I understand these rules can be confusing, that is why we will use the following flight plan to explain how these rules apply in real-life scenarios. For the entire article, let’s use the following information:

Here is the departure, arrival, and approach procedure we will be using for this scenario

So what should the pilot do if he remains in IMC conditions.?

• 1) Troubleshoot
• 2) Squak 7600
• 3) Route
  • According to § 91.185 IFR lost comm, he must follow the last assigned route. Remember AVEF: First assigned, then vectored; if he has not been assigned a route, use the expected route. Finally, if there is no assigned or expected route, fly the filed route. Before the radio failure, he was being radar vectored and was expecting to join the WINCO transition. WINCO transition starts from over DHP VORTAC then on DHP R-322 to WINCO INT. In conclusion, he proceeds directly to DHP and continues flying the WINCO transition.

• 4) Altitude
  • Select the highest of
    • M -3,000 ft (OROCA in the quadrant)
    • E – 8,000 ft (10 min after departure)
    • A – 2,000 ft (Assigned on the clearance)
  • In simple words, as soon as he starts turning direct DHP, he should climb to 3,000 ft, which is the highest altitude for that segment. After 10 min, he can continue the climb to 8,000ft. Why not climb to 8,000 ft right away.?
    • According to the AIM 6-4-1
      • “If the pilot received an “expect further clearance” containing a higher altitude to expect at a specified time or fix, maintain the highest of the following altitudes until that time/fix:
        • (1) the last assigned altitude; or
        • (2) the minimum altitude/flight level for IFR operations
      • Upon reaching the time/fix specified, the pilot should commence climbing to the altitude advised to expect.”

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Easy right? Let’s try with another scenario. Remember we are simulating the pilots is in IMC all the time

So what now?

• 1) Troubleshoot
• 2) Squak 7600
• 3) Route
  • Follow the last assign route, WINCO DCT RSW.BRGDE7 KTPA

• 4) Altitude
  • Select the highest of
    • M -3,000 ft (MEA of the flying segment)
    • E – 8,000 ft (Was expected 10 min after departure)
    • A – 6,000 ft (Last assigned before the failure)
  • Maintain 6,000 ft for the remaining part of the flight. But why not 8,000 ft?
    • According to the AIM 6-4-1
      • If the radio failure occurs after the time/fix specified, the altitude to be expected is not applicable and the pilot should maintain an altitude consistent with 1 or 2 above( minimum IFR Altitude, last assigned). If the pilot receives an “expect further clearance” containing a lower altitude, the pilot should maintain the highest of 1 or 2 above until that time/fix.

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Awesome, now that we understand what route to fly and to what altitude to climb in a lost communication scenario under IFR, let’s talk about what you will do as you get closer to the airport. When we talk about altitude § 91.185 IFR lost comm is very clear. You must fly the highest of the minimum IFR altitude (OROCA, MEA, MOCA, etc.), assigned, and expected according to the sector or segment you are flying. However, at some point, you need to start to descend. Start by calculating your TOD, but always take into consideration the IFR altitudes for the segment. That’s the only way you will guarantee obstacle clearance.

Let’s continue with the previous scenario, pretending the pilot never regains radio contact with ATC. His clearance limit remains the same. The pilot flew the assigned route at 6,000 ft, and according to the weather forecast previously used for flight planning, they expect ILS 19R. But we start what a clearance limit is? According to the AIM, clearance limit is a fix, point, or location to which an aircraft is cleared when issued an air traffic clearance. Or according to ICAO is the point to which an aircraft is granted an air traffic control clearance. Great, now that we have that clear, let’s begin.

So when can the pilot commence the descent into the approach?

• Let’s ask ourselves this question. Is the clearance limit a fix where the approach begins.? In the last assigned clearance before the radio failure, the clearance limit was KTPA. As a result, we use the second part of § 91.185 IFR lost comm IFR (3).
  • The pilot must “Leave clearance limit at the EFC time or upon arrival over the clearance limit. Proceed to a fix from which an approach begins and commence descent and approach as close as possible to the ETA as calculated from the filed or amended ETE.”

CFR § 91.185 “commence descent and approach as close as possible to the ETA”. The pilot took off at 18:01Z; the ETA is 20:00Z. Crossing PIE VORTAC at 19:54z is only 6 minutes away, plus N123EC still has to fly 20.4nm from PIE to the initial approach fix of the ILS 19R at KTPA. In a few words, they can continue on the feeder route into the IAP and commence the approach.

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That was really fun, right? Let’s look at another scenario!

Not a good day for this pilot, right? So what now?

• 1) Troubleshoot
• 2) Squak 7600
• 3) Route
  • Follow the last assign route, After PIE VORTAC proceed to MERRA

• 4) Altitude
  • Select the highest of
    • M -3,000 ft (MEA of the flying segment)
    • E – None
    • A – 4,000 ft ( Last assigned )

• 4) When to start the approach?
  • Is the clearance limit a fix where the approach begins?
    • Yes – Start the descent and the approach as close as possible to the EFC time

In this scenario, N123EC will continue flying at 4,000 ft on the feeder route to MERRA. The pilot should be over MERRA around 19:38Z. His EFC is 2010z; he should be ready to hold until that time and then start the descent to 3,000 ft and commence the approach.

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That was a lot to take in a single day. We have one more thing to add here, some departures and arrivals procedures have specific routes and altitudes in case of lost comms. Make sure to review this as part of your flight plan preparation, and if you are flying with someone, introduce it in the briefing.

IFR Lost communication specific procedure in a departure

IFR Lost communication specific procedure in an arrival

IFR Lost communication is something that we can talk about endlessly. There are infinite scenarios that an examiner can use in a check ride, our job as a pilot is to be open minded and never stop learning. A good pilot is not one who knows everything. A good pilot is one that is humble enough to say I don’t know this and ask how can I learn more about this topic.? I know a lost communication in total IMC is getting rarer, but it can happen so be ready.

Don’t stop here, let’s keep learning!