Thanks for your attention and comments to my posting on this accident. I have added a fair amount of additional material over the last few days to answer some lingering questions. Let me know if something is wrong or missing. Of course, with real flight data a more conclusive analysis would be possible, plus awareness of the actions onboard.
Having dug as deep as I can with the limited information at hand:
1) The flight plan from SLVR to SKRG with 77 aboard is beyond the legal range of this airplane, even with auxiliary tanks. The same plane had flown the same city pair in reverse on Nov 4, with with even a longer stage length of over 4:33. The investigation will have to conclude on this point as it appears the flight planning was reckless.
2) FEED LO LEVEL warning would have been raised at least 150 km from SKRG. Each feed tank has a dedicated gage for constant monitoring. There can be no doubt the flight crew knew they had a little more than 20 minutes of fuel left, at that point, and counting.
3)There appears to have been sufficient fuel for a straight-in approach, and after one circuit around the holding pattern. The decision to turn outbound on the second circuit left fuel exhaustion inevitable.
4) ADS-B position data appears to be driven from an IRS source, not GNSS. The departure position was offset by 2 km. Evaluating a few other flights of similar duration suggests another 2 km drift could be expected, or for this flight the position uncertainty is about 4 km (2 nm). The northern arrival suggest an easterly offset of less than 1 nm.
5) LMI2933 entered and held over RNG VOR/DME. The reported position was offset about 10 nm south of the VOR. While IRS error might account for 2 nm of the error, the remaining 8 nm offset is puzzling. The final resting place and the actions through the last few minutes are most consistent with the airplane operating 8-10 nm south of RNG. This issue should be resolved in the investigation.
6) The necessary glide ratio while holding at 21,000 feet peaked at about 11:1 on the backside of the pattern (to SKRG runway 01).
7) The necessary glide ratio from the last reported position had increased to 13:1 (due to there relatively steep descent).
8) The RJ85 operates with no fuel (windmilling engines, no APU, no standby generator) by using a battery to power one comm/nav set, standby instruments, and hydraulic power for landing gear extension and braking. The pitch and roll controls are mechanical. The rudder control is possible only if the windmilling on Eng 3 is sufficient and only if the crew isolates the standby generator. Flap, spoilers, air brake: are not powered. Plan on flaps up landing.
9) RJ85 predicted glide ratio is 15:1 flaps up at best glide speed.
10) Normally should only extend gear when landing is assured, as glide ratio drops to 6:1 with gear extended.
11) LMI2933 descended from 21,000 feet presumably under power, with flameout approximately at 15,000.
12) In the descent the airplane was slowed to what appears to be flaps/gear down approach configuration.
13) The estimated glide ratio from the last reported position to the crash site is about 5.7:1 (matching predicted gear down glide ratio of 6:1).
14) LMI2933 appears to have been capable to glide to SKRG runway 01 until the point that the flight crew (apparently) pre-maturely extended flaps and gear.
I have extracted info from a copy of the RJ85 FCOM vol 1. It would help if someone could send me vol 2 and vol 3.
Satcom Guru: LMI2933 LAMIA AVRO RJ85 Medellín Deadstick