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3.3 ABORT OR ABORT/STAGE DECISION
[i]An abort or abort/stage decision is made when a malfunction has been detected that will affect crew safety or the capability of the LM to abort from powered descent... The decision to abort is based on the occurrence of one of the following: [list][*](a) Propulsion... Impending DPS propellant depletion
[*](c) Trajectory constraints: Violation of specified abort limits on MCC-H displays[/list] 4.3.7 Low Level Propellant Monitoring
...the ground will assume the prime responsibility for warning the crew of impending DPS fuel depletion. Using the time at which the ground observes the DPS propellant-level low (DES QTY) "light on" signal as a zero reference point, MCC-H will give voice cues to the crew indicating 30 and 60 seconds elapsed time, and fuel depletion. The timing Of these cues will be biased (to account for transmission delay, fuel usage prediction errors, and sensor errors) so that the crew will hear "fuel depletion" when there will actually be 20 seconds of hover thrust (6 seconds of full thrust) remaining for an immediate landing or DPS abort.[/i]
[i]3.1 GROUND RULES
...the DPS should be used in abort situations whenever possible, even if there is only a few seconds burn available, to aid in establishing a positive radial rate and to improve propellant margins.[/i]
[i]1-23 The Command Pilot may initiate such inflight action as he deems essential for crew safety.
2-25 LM Powered Descent: If a systems failure occurs and a choice is available: [list][*]Early in powered descent... (up to PDI +5 minutes)
[*]During the remainder of the powered descent, it is preferable to land and and launch from the lunar surface than to abort. Only those systems failures and trends that indicate impending loss of the capability to land, ascend and achieve a safe orbit from the lunar surface, or impending loss of life support capability will be cause for abort during this period.[/list] 5-90 Powered descent will be terminated for: (H) Violation of the time biased (20 sec) DPS abort boundary.
5-91 There are no trajectory or guidance constraints which are cause for abort after crew take over of powered descent.
25-12 The total continuous burn time of the descent engine shall not exceed 910 seconds of continuous operation independent of thrust level (based upon a lunar mission duty cycle).
25-18 If possible the DPS will not be burned to propellent depletion, where ever possible the abort stage sequence will be initiated at low level plus 20 seconds during an abort from powered descent, however, at crew option abort stage sequence may be initiated at low level if a safe abort stage capability exists.
25-37 Low level confirms insufficient propellant to land - (B) Powered descent: Abort stage 20 seconds after low level[/i]
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