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SID lost communication procedure vs 91.185

Asked by: 1855 views Instrument Rating

I was looking at a lost communication procedure for NARROWS ONE DEPARTURE at KTIW which says “If no transmissions are received for 3 minutes after departure, climb to field altitude direct to SEA VORTAC, thence via assigned route” and started wondering how it is related to the comm failure reg on 91.185. The clearance from the ground usually sounds like “…cleared to xxxx via Narrows One Departure, then as filed, climb and maintain 2000, departure frequency…”

First, it’s reasonable to assume that I’m supposed to fly the lost comm procedure as depicted on the SID if it’s in IMC. But if it’s in VFR, am I supposed to land as soon as practical, or still fly the lost comm procedure as specified by the SID? The procedure would take me to SEA VOR which is directly over KSEA where airline jets are flying underneath or even possibly at the same altitude if some of them decide to go missed. I feel like I would be creating unnecessary hazards for myself and others when I can just land as soon as practical under VFR.

I guess my question is, when does 91.185 supersedes the lost comm procedures specified on SIDs and vice versus? My guess is that 91.185 always takes precedence and that the AVEF applies in this scenario because SID is considered “assigned route” which should be flowed as long as it’s IMC, but in VMC I should land as soon as practicable. Looking forward to hearing any response!

2 Answers

  1. Best Answer


    Bryan on Apr 19, 2022

    That’s a thoughtful question, but I think you have it backward.

    91.185(a) begins, “Unless otherwise authorized by ATC…” You got clearance on the ground to proceed “via Narrows One Departure.” They have the chart right there and are aware that they’re giving you alternate lost comms procedures as noted on the SID. So you follow the SID under 91.185(a) because it was cleared by ATC and the rest of 91.185 doesn’t apply until you overfly the SEA VORTAC at your filed altitude.

    Generally, the regulations are the baseline rules and departures from those rules (everything from airspace configurations to approach charts to NOTAMS) are noted as appropriate. So if you’ve been cleared for a SID or any approach, follow what is on that plate because that’s what ATC cleared you to do–then worry about the lost com procedures in 91.185 if you even still have to.

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  2. Joe123 on Apr 19, 2022

    Thanks for your reply Bryan!

    That makes sense. It seems that 91.185 applies when ATC hasn’t authorized to do any procedure, but in this case the SID is authorized so it must be prioritized. Then, 91.185 kicks in upon reaching SEA VOR after which I’m either landing as soon as practicable under VFR conditions or fly the route and altitude according to AVEF and MEA rules to navigate under IFR.

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