Apollo 13, but in LEO

[VQ]

Crossposting https://forum.cosmoquest.org/showthread.php?165765-Apollo-13-explosion-occurs-whilst-in-Earth-orbitfor general interest. In particular, a poster there linked http://klabs.org/history/apollo_experience_reports/tn-d7151_csm_rcs.pdf, which indicates on the page labeled 2 (7/55 in the PDF) that a contingency deorbit for LEO Apollo missions was developed that used both the SM and CM RCS systems to achieve reentry if the SM SPS failed. That was new information for me; had anyone else heard of that procedure?

[bknight]

I had not read that document until recently, but that contingency plans for emergency situations would have been thought out and written into the mission profile.  All one has to do is to remember  previous launches, when the PAO announces "milestones" during launch i.e. from https://www.jsc.nasa.gov/history/mission_trans/apollo11.htm.

Mode 1 Bravo, 1 Charlie from page 13/633 from Apollo 11.

[ka9q]

There were lots of contingency aborts in Apollo planning. As bknight says, that's what those "Mode 1 Bravo" callouts were about during launch. Countless contingency "PADs" (burn maneuvers) were read up to the crew at various points in the flight so they could be used to return to earth on their own at predefined points in the flight if they were to lose communications.

[Geordie]

It seems there were 8 abort modes:

https://en.m.wikipedia.org/wiki/Apollo_abort_modes

Pad abort, T-5:00-0.

Mode I, using LES:
Alpha - 0-3000m.
Bravo - 3000-30500m
Charlie - 30500m-LES jettison.

Mode II, early during S-II burn.

Mode III, aka Contingency Orbit Insertion or S-II to COI.

S-IVB to orbit.

Mode IV, during S-IV burn.