But as you advance in your ratings from private to instrument to commercial, you start to fly more sophisticated and more expensive aircraft. Building solo time can be difficult due to insurance requirements around minimum experience, or due to the lack of a appropriate ratings (e.g., working on a multi-engine rating after earning commercial in a single-engine airplane). If a student simply doesn't have the requisite level of experience, then they can't rent from an FBO, placing a burden on getting solo experience.
For this reason, the FAA has created a substitute for solo in the requirements for flight experience for a commercial rating (61.129). The wording is that you must either be solo or "performing the duties of pilot in command...with an authorized instructor on board."
To indicate this sort of a flight on MyFlightbook, you should log the flight and attach the "Duties of PIC" (DPIC) property and the "Instructor on Board" (IOB) to the flight. (I'll refer to this below as "DPIC/IOB" time)
There is often confusion about this, and I have on more than a few occasions received an email complaining that MyFlightbook is not crediting all of the time it should be crediting, or is missing their long cross-country flight.
The idea is that this is supposed to emulate solo flight, so the instructor is there not to teach you, but rather to satisfy insurance restrictions. You're doing all of the work as if you were in fact in solo flight. The instructor, therefore, should essentially be sitting on their hands for the flight. The mistake people typically make here is that they read "instructor on board" as meaning "I can log dual."
Unfortunately, this is a misreading of the regulation. The normative legal interpretation from the FAA can be found in the 2014 FAA "Kuhn" interpretation (or Google the phrase "FAA duties of PIC Kuhn"): you cannot simultaneously receive instruction and count flight towards 61.129(a/b)(4).
The money quote from the Kuhn letter is "Because this flight time is a substitute for solo flight time, the pilot is not receiving instruction and therefore cannot log this time as dual instruction received."
For this reason, MyFlightbook subtracts out any dual instruction that is logged from the amount of DPIC/IOB time to determine how much time can credit towards 61.129's requirements.
Note too, that since this is a substitute for solo flight, you must not log it as solo either (after all, you're not alone in the aircraft).
MyFlightbook computes a flight's contributions towards solo requirements as follows:
- Compute an effective DPIC/IOB time as
MIN(DPIC/IOB, Total Time - Dual Received)
- A flight with 2 hours of DPIC/IOB, 2 hours of total time, and 2 hours of Dual yields
MIN(2, 2 - 2) = MIN(2,0) = 0.
- A flight with 2 hours of DPIC/IOB, 2 hours of total time, but only one hour of instruction, yields
MIN(2, 2 - 1) = MIN(2,1) = 1 hour.I.e., I'm removing the hour of instruction per Kuhn, but the other hour can count as DPIC/IOB.
- A 2 hour flight with 60 minutes of instruction and 90 minutes DPIC/IOB yields
MIN(1.5, 2 - 1) = MIN(1.5, 1) = 1 hour.I.e., the flight is ambiguous, but at most one hour of this flight could possibly contribute time here, so I'll give you the hour.
- Compute an effective solo time of
MAX(explicitly logged solo time, effective DPIC/IOB)
- Compute an effective night VFR solo time of
MIN(effective solo time computed above, Night - IMC)
- For any activities such as takeoffs/landings or a long cross country that must have been performed while solo, add them to your experience if the effective solo time is greater than 0.
- Finally, the various 61.129(4) requirements computed using both actual solo time and the effective substituted solo time. After all of your flights are examined and the experience is summed up, MyFlightbook will report your progress using either exclusively actual solo time, or exclusively DPIC/IOB time (whichever has more time recorded), but not both. This is because you cannot mix-and-match: all of the solo time in 61.129 MUST be actual solo time or it must all be DPIC/IOB time (see the FAA's 2016 "Grannis" interpretation for details).
So by all means, go out and build your "solo" time with an instructor on board. But don't log it as instruction received.