November 12, 2012 at 11:17 am #83940
I saw on the news a 1980 Cessna 421C went down in the shaver lake area of Fresno county, CA on 11/10/12. The tail number was N700EM and from the debris field an inflight breakup is suspected. The father and son perished in the accident. I did not know the pilot or passenger but it is sad day for their families, friends and the flying community.
From the flightaware record, it look like the plane was flying recently and often, including some high altitude flights earlier in the year. This flight was out of the norm vs recent, and was a 6:40 pm departure, 5 hr cross country (1400 statue miles) at 27,000 feet with a 1:40 AM arrival. The service ceiling is 30,000 ft (but I don’t think anyone has RVSM so it is really 28,000 feet). My tables don’t go above 25,000 feet – but it looks like his time to climb was about 32 minutes (makes sense extrapolating from the charts). The flight was in level flight for about 6 minutes with a ground speed of 220 kts suggesting a fairly high (but reasonable) power setting. I am not sure what the winds aloft were, but the climb speed was 200 kts GS.
At 6 min into level flight at FL270 something happened to cause what ended as an inflight breakup. The accident was near the base of the Sierra mountain range but at that altitude they would have been well clear of any terrain. Not sure about the weather/winds, etc. At FL270, Time of useful consciousness should be around 3-5 minutes (less if very sudden).November 14, 2012 at 3:16 am #97065rwelshParticipant
Eric, I think you were reading the MPH not the knots column for his speed. Actually that seems low for an eastbound trip although I did not see the winds aloft for that period. I don’t know the area where it came apart, but it must have been just east of the Sierras. I wonder if there was a rotor cloud going on that night.November 14, 2012 at 7:41 am #97066quote RWELSH:
Sorry, I had read it as MPH. That would be slow for ground speed, especially east bound where the prevailing winds would be a tailwind. The crash site was west of the sierra’s, in the western foothills – so they were not in high terrain yet.November 14, 2012 at 11:20 pm #97069
I wonder if the data reported by FlightAware at 10:19 and 10:20 were from real radar returns or extrapolated by Flightaware – most likely real returns. If that is the case, the avionics were still receiving power until at least 10:21 so the wing was intact for at least the first several minutes. Terrible accident – they must have been conscious through at least a portion of the ride down.
10:18PM 194 kts 27000 Ft 0FPM
10:19PM 194 kts 27000 Ft -1080FPM
10:20PM 316 kts 24900 Ft -2100FPMNovember 15, 2012 at 4:19 am #97071quote COCHRANE:
From what I seen, the FAA or flightaware sometimes “coasts” the position of a plane based on the last heading/airspeed. Because of this, I am not sure if the last airspeed is real. The altitude is based on the return, so this would be accurate unless their was a static system or encoder error.
194 kts GS with no wind is about 125kts indicated (standard temps). My experience is below 140 kts indicated in cruise flight the angle of attack is steeper and the drag higher. The only time I encounter this is mountain wave conditions (in the downdraft). If you let the AP hold level flight it will keep pitching up and you might not notice the speed drop.
Could they have been conserving fuel for the long x-country (5 hrs planned) and gotten too slow?November 15, 2012 at 5:03 pm #97074
Yikes… Pretty rare for a twin Cessna to have an inflight breakup isn’t it? Especially strange is that this is a post-serial 801 aircraft which has the “improved” spar (different metallurgy) that wasn’t affected by the SID.
One report says that neither the tail nor the wings were found, which points to a really violent departure from flight. Could have just been a routine loss of control while IFR and he pulled back too hard, but dang… I’ve got a hard time imagining pulling the wings off a 421.
Airplane appears to have flown regularly, but not many long flights. This was an exceptionally long flight for a 421… 5:05 planned flight time is longer than I’ve sat in a 421.
RobertNovember 16, 2012 at 3:21 am #97078quote RCJOHNSON:
The other thing that is odd is the time of departure is late in the day with a ~2 AM arrival. Why go up to FL270 unless you have a good tail wind (but if you have a good tailwind then why is the GS so slow?) Also, they filed for an aggressive 230kts. With an actual around 194 kts, that would make it a 6 hr x-county and about 242 gallons. One possible concern would be if they leveled out and pulled power to conserve fuel and the turbo’s ran down. At 27,000 feet it could take ~minutes to spool them back up. Could they have lost pressurization trying to get the engines/turbo’s back on line? Got too slow holding altitude?
My limit is FL230, but prefer between 18,000 and FL210. FL270 is an unforgiving environment for a piston twin. FL270 is a 10,000 ft cabin best case. I am not sure at what power setting pressurization would drop off, but I suspect around 40-45% power.
FYI, looking at the range profile in the POH, that length trip would not be possible with standard tanks at any altitude or power setting. With standard tanks + one aux it would just be possible (but well beyond my comfort level)December 2, 2012 at 4:54 pm #97251
Preliminary is out.
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