Flight control provided satisfactory operational support for all required areas during the Apollo 15 mission. A number of the problems that were encountered are discussed elsewhere in this report. Only those problems that are unique to flight control, or have operational considerations not previously mentioned, are presented in this section.

A radial velocity error in the launch vehicle guidance system at earth-orbit insertion necessitated a navigation update to minimize the subsequent planned midcourse correction. Without the update, a 32-ft/sec velocity change would have been required at 9 hours. After updating the state vector, the actual midcourse correction was approximately 5 ft/sec (See section 6.5.)

As a result of the service propulsion system thrust light anomaly discussed previously, the crew was requested to deactivate both pilot valve circuit breakers immediately after the light was first observed. This measure was instituted to safeguard against an inadvertent firing until the problem could be thoroughly understood. To isolate the cause of the Malfunction, a test was conducted in conjunction with the first midcourse correction and the problem was resolved, including the development of workaround procedures. The crew was instructed to power down the entry monitor system scroll in order to eliminate the nuisance factor of a constant false light indication until the use of the entry monitor system was required.

During the first period of scientific instrument module activity for film advancement, the ground station (Madrid) had a problem in locking onto the FM subcarrier. This was determined to be a site procedural problem. All sites were briefed on the problem and no subsequent problems were encountered.

After lunar module ingress and the crew's description of the broken glass cover on the range/range rate tapemeter, ground tests were performed to verify that the tapemeter would function properly with the glass broken, exposing the inside of the instrument to the cabin atmosphere. A careful review of procedures was made to evaluate crew monitoring techniques during descent. A technique was developed to use the abort guidance system for displaying raw landing radar altitude data should the tapemeter and the primary guidance and navigation system fail, but the technique was not voiced to the crew.

At acquisition of signal during the 12th lunar revolution, the lunar module crew reported that they had been unable to separate from the command and service module and that the Command Module Pilot was investigating the probe umbilical integrity. An off-scale high docking probe temperature was indicative of a possible umbilical problem. The umbilicals were found to be the source of the problem, and the condition was corrected. Meanwhile, the crew had been advised by Mission Control that undocking and separation were not time critical. The separation was achieved about 36 minutes late. Landmark tracking was deleted during the umbilical integrity problem, but adequate data were later obtained when the command and service module was in a higher orbit.

During the sleep period after the standup extravehicular activity, the descent oxygen was being depleted at a rate about 1 pound/hour greater than expected. The oxygen quantity was not critical, but the descent oxygen tank pressure was critical to allow a full portable life support system recharge for the third extravehicular activity, The crew was awakened approximately 1 hour early to locate the leak. They found that the leak was caused by the urine receptacle device being inadvertently left open. The early completion of this task allowed preparations for the first extravehicular activity to start about 20 minutes early.


Adequate support was provided by the Mission Control Center and Manned Space Flight Network. Although a number of minor discrepancies and problems arose during the mission, there was no interruption of mission support. The most significant problem, in terms of potential impact, was an error in a command module computer delta-velocity return update. The error was not discovered until after the load had been transmitted to the spacecraft. A different load was then generated and transmitted to correct the data in the command module computer. A correction to the software will be made for the next mission.


The Department of Defense provided recovery support in accordance with the mission planning for Apollo 15. Ship support for the primary landing area in the Pacific Ocean was provided by the helicopter carrier USS Okinawa. Active air support consisted of five SH-3G helicopters from the Okinawa and two HC-130 rescue aircraft staged from Hickam Air Force Base, Hawaii. Two of the helicopters, designated "Swim 1" and "Swim 2", carried underwater demolition team personnel and the required recovery equipment. The third helicopter, designated "Recovery," carried the flight surgeon and was utilized for the retrieval of the flight crew. The fourth helicopter, designated "Photo," served as a photographic platform for both motion picture photography and live television coverage. The fifth helicopter, designated "Relay," served as a communications relay aircraft. The two HC-130 aircraft, designated "Hawaii Rescue 1" and "Hawaii Rescue 2," were positioned to track the command module after it had exited from S-band blackout, as well as to provide pararescue capability had the command module landed uprange or downrange of the target point. The inset in figure 11-1 indicates the relative positions of the recovery ship and HC-130 aircraft prior to landing. The recovery forces assigned to the Apollo 15 mission are shown in Table 11-I.

11.3.1 Command Module Location and Retrieval

Based upon a navigation satellite (SRN-9) fix obtained at 2o46 G.m.t., August 7, the Okinawa's position at the time of command module landing was determined to be 26 degrees 12 minutes 54 seconds north latitude and 158 degrees 13 minutes 12 seconds west longitude. The ship-based aircraft were initially positioned with respect to the target point as shown in figure 11-1, and they departed station to commence recovery operations after visual contact had been made with the command module. The Okinawa is shown in figure 11-1 as it was positioned at the time of command module landing.

Radar contact with the command module was first reported by the Okinawa at 2037 G.m.t. This was followed by an S-band reported by Hawaii Rescue 1 at 2038 G.m.t. and VHF recovery beacon contact by the Okinawa at 2041 G.m.t. At approximately the same time, all recovery force aircraft established VHF recovery beacon contacts. Shortly thereafter, two-way voice communication was established between the Apollo 15 crew and recovery forces.

Visual sighting of the command module occurred at 2041 G.m.t. by the Swim 2, Photo, and Relay helicopters. At the time of initial sighting, the command module was descending on three normal main parachutes. At least two pilots, in different aircraft, saw one main parachute stream at about 6000 feet.

The command module with the two main parachutes properly inflated and one collapsed, landed at 2045:53 G.m.t., approximately 32 seconds earlier than predicted, and remained in the Stable I flotation attitude. The landing point was calculated using the navigation satellite fix of the shin's position at spacecraft landing and a radar sighting which established that the command module was 6.6 miles distant on a bearing of 145 degrees east of north. Based upon these data, the landing point coordinates were 26 degrees 7 minutes 30 seconds north latitude and 158 degrees 9 minutes west longitude.

After a visual inspection of the command module and assurance from the crew that they were all in good condition, the Swim 2 helicopter managed to secure one of the main parachutes before dropping swimmers who installed the flotation collar on the command module. The Swim 1 helicopter dropped swimmers to secure a life raft to the forward heat shield. One main parachute and the heat shield were retrieved.

The flight crew was delivered aboard the USS Okinawa by the recovery helicopter at 2125 G.m.t. No quarantine procedures were required for this mission. Command module retrieval took place at 26 degrees 7 minutes north latitude, 158 degrees 10 minutes 12 seconds west longitude at 2220 G.m.t. on August 7.
The flight crew remained aboard the Okinawa until 1655 G.m.t., August 8, and were then flown to Hickam Air Force Base, Hawaii. After a brief welcoming ceremony, a C-141 aircraft flew them to Ellington Air Force Base, Texas.

The command module was offloaded at North Island Naval Air Station, San Diego, California, on August 17. It was deactivated and delivered to Downey, California, on August 20.

The following page shows a chronological listing of events during the recovery and postrecovery operations. ( Figure)

11.3.2 Postrecovery Inspection

Visual inspection of the command module in the recovery area revealed the following minor discrepancies: