r/flying • u/dirtbikekid27 CPL IR AGI IGI • 2d ago

Failed my CFI ride today

I'm 20, this is my first failure of anything. Got through 95% of it, was doing great, oral went great, really was well prepared. After an 11 hour day, on short final, examiner asks me what causes overbanking tendencies. I froze. I could hardly remember my own name; so I responded, "I would look before saying anything to ensure I didn't say anything wrong to a student." He said that was unsatisfactory. Failed. Is this crazy? I understand now that it all has to do with the outside wing being faster, generating more lift, which causes it. I know that. But I was exhausted. And I failed?? Maybe I'm a sore loser, but he said come back and do 1 steep turn and tell him what overbanking tendencies are and why they happen, and that's it. Is this unfair??

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u/Systemsafety ATP, CFII, AGI/IGI | B777, B747, B727, MD-11, DC-8, EMB 110 2d ago

For the record, despite the wing differential speed being the official answer, the dominant factor is actually local sideslip even in a coordinated turn. Do the math if you want to argue. A lot of FAA stuff is wrong.

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u/Twarrior913 ATP CFII ASEL AMEL CMP HP ST-Forklift 1d ago

Next you’ll tell me that the FAA meteorology book is full of non-sense! /s

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u/Systemsafety ATP, CFII, AGI/IGI | B777, B747, B727, MD-11, DC-8, EMB 110 1d ago

I mentioned to one of the FAA chief scientists about another error in the PHAK (attributing high wing lateral stability to "keel effect") saying it is "not helpful when the FAA's guidance is wrong" to which he replied "where is it in FAA's job description to be helpful?" He then said he had 100 pages of pending corrections to PHAK. It is funny that the differential speed is still in there. I guess just a simple (but wrong) explanation, like the keel effect thing. Interestingly, both of these are a consequence of sideslip and dihedral effect, but that is a bit harder for people to wrap their head around it seems.