Say Again Apollo 14 · Gallery of lunar exploration
← Stop 2 · The page

The page - Historical Evidence

The page - Historical Evidence

The following claims appear in stop 2, in Marion and Theo's lines or in the archive clips, and are assessed against primary and secondary sources. Numbered citations refer to the Sources list at the end of this page. Times are ground elapsed time (GET), counted from lift-off on 31 January 1971.

Marion and Theo are invented, and so is the gallery. Their story is not assessed here: only what they say about Apollo 14 and about read-backs, and the archive recordings they listen to.

From the dialogue

Claim: In air traffic control, the controller reads a line, the pilot reads it back, and the controller checks it and corrects it if it is wrong.

Status: Confirmed

Line: "I read a line, the pilot reads it back, I check it. Wrong, I say it again. Nothing counts until it comes back right."

Under ICAO rules, "The controller must listen to the read-back to ascertain that the clearance or instruction has been correctly acknowledged by the flight crew and shall take immediate action to correct any discrepancies revealed by the read-back" [7, quoting ICAO Annex 11, 3.7.3]. The read-back "gives the controller an opportunity to confirm that the message has been correctly received, and if necessary, to correct any errors" [7]. In Australia the requirements are set out in the AIP, GEN 3.4; if a read-back "is incorrect or incomplete, ATC will need to confirm your understanding" [8].

Claim: Mission Control and the Apollo crews worked the same way.

Status: Confirmed

Line: "Textbook. Same with us."

Reading numbers back was routine on the Apollo 14 air-to-ground loop. Minutes after the first call about the abort bit, Roosa read back a block of manoeuvre data and Haise answered "That was a good readback, Kitty Hawk" [2, p. 342]. The correction in this stop's last clip opens with the same word: "Correction on your readback" [2, p. 362].

Claim: The first version of the fix went up an hour and a half before the descent.

Status: Confirmed

Haise read up the first version at 106:34:17 ("The procedure is VERB 25 NOUN 7 ENTER; 105 ENTER; 400 ENTER; 0 ENTER") [2, p. 357]. The descent engine lit at 108:02:26.52 [1, p. 8-10], 1 hour 28 minutes later.

Claim: Mitchell wrote it down as it came.

Status: Confirmed

Just before the read-up Shepard asked Houston to stand by "while he's getting something to write on". Mitchell then asked, "Do I have enough room to write just in the space on my PDI chart?", and settled on "... room on the DPS burn card, Fred. Go ahead with it" [2, p. 357].

Claim: Mitchell's read-back of the first line had two slips, and both were caught.

Status: Confirmed

Lines: "'Is it four thousand?' He wasn't even sure. Two slips in one line." / "And both caught."

Haise read up "105 ENTER; 400 ENTER". Mitchell read back "05 ENTER. Is it 4000 ENTER?", one wrong number and one he queried. Haise corrected both, spelling out "400, four zero zero", and Mitchell's second read-back was right: "VERB 25 NOUN 07 ENTER; 105 ENTER; 400 ENTER; 0 ENTER" [2, p. 357]. (The mission commentary transcript has the first read-back without "Is it" [3, 304/1]; the clip follows the voice transcript.)

Claim: With the fix in, only the backup computer could abort.

Status: Confirmed

Line: "The catch: with that code in, only the backup computer could abort."

Haise, at 106:36:03: "What we've done, then, is locked out P70 and P71, so any aborts have to be done on the AGS" [2, p. 358]. The AGS was the lunar module's abort guidance system, which the mission commentary called "the secondary guidance system in the LM" [3, 304/4]. The Mission Report says the same of the final version: "The abort capability of the primary guidance system was lost by use of this procedure. Therefore, it would have been necessary to use the abort guidance system if an abort situation had arisen" [1, p. 8-11].

Claim: Houston then came back with a better version.

Status: Confirmed

At 107:31:51 Haise told the crew they had "found ... a little slicker way of doing this", one that "allows us to start PDI in the right configuration, switchwise. And, we can make an entry before we get to ullage or ignition that will get by that problem area" [2, p. 362]. MIT's memo explains why it was better. The first fix "left open a window between ignition and the resetting of the flag where the abort signal would cause the abort guidance to take effect". The new one "would eliminate the window and absolutely prevent the abort button from having any effect" [4].

Claim: It was worked out while the crew were behind the Moon, out of radio contact.

Status: Confirmed

Line: "They worked it out while the crew were behind the Moon, out of radio contact."

Houston lost contact at about 106:44, after "We're just about to LOS" (loss of signal), and called Antares again at 107:28:14 [2, pp. 360-361]. Haise said the new way had been found "in the interim of time around the backside there" [2, p. 362]. The mission commentary at the time: "Now behind the Moon nearing the start of the 14 revolution" [3, MC-305/1]. MIT's memo credits the final version to "MIT, Cambridge" [4], which is why the line says "they", not "Houston".

Claim: When they came round again, there was half an hour to go, and a new list.

Status: Confirmed

The new list was read up from 107:31:51 [2, pp. 362-364]. The descent engine lit at 108:02:26.52 [1, p. 8-10], about 30 minutes later.

Claim: A real page carries the first line of the new code, handwritten in the margin.

Status: Confirmed; whose page it is, is not known

A scan of page 5 of an Apollo 14 LM Timeline Book, printed "DATE 11/20/70" and headed "BACKSIDE TO PDI", has "V21 N1E / 1010E / 107E" handwritten in the right margin. A drawn line joins it to the printed step "ENTR, √DET" [5]. That matches Haise's read-up at 107:33:49: "After the ENTER and check DET, Ed; we need a VERB 21 NOUN 01 ENTER; 10 10 ENTER; 107 ENTER" [2, p. 362]. The Lunar Surface Journal hosts the scan without a caption. Who owned the copy, whether it flew and where the paper is now are not recorded [5][6]. The case in the gallery holds a facsimile.

Claim: Theo reads the margin as "V twenty one, N one, E. Ten ten, E. One-oh-seven, E."

Status: Confirmed

The margin reads "V21 N1E / 1010E / 107E" [5]. V, N and E are the keypad's VERB, NOUN and ENTER, as in Haise's read-up [2, p. 362].

Claim: That line is the first line of the new code.

Status: Confirmed

Line: "The first line of the new code."

It is the first of the four entries in the final version [2, pp. 362-364]. MIT's memo writes it in the same form, "V21, N01E, 1010E, 107E": it set the computer's mode register to the abort program (P71) "after P63 integration and before ignition" [4]. The Mission Report: "Part one consisted of loading the abort stage program number into the mode register" [1, p. 8-11].

Claim: Reading it back, Mitchell said "one-oh-one" for "ten ten", and it was caught straight away.

Status: Confirmed

Line: "One-oh-one. He dropped a digit, and they had it straight away."

Mitchell read back "VERB 21 NOUN 1; 101 ENTER; 107 ENTER" at 107:34:22. Sixteen seconds later Haise came back: "Correction on your readback. It's VERB 21 NOUN 01 ENTER; 10 10 ENTER; 107 ENTER" [2, p. 362][3, 306/2].

From the archive clips

Claim: Mitchell, 106:34:55: "Okay. I'll read back. VERB 25 NOUN 07 ENTER; 05 ENTER. Is it 4000 ENTER? 0 ENTER." Haise, 106:35:08: "Okay, Ed. It's - it's VERB 25 NOUN 7 ENTER. Then, 105 ENTER; 400, four zero zero, ENTER; 0 ENTER."

Status: Confirmed

Both lines are word for word in the NASA voice transcript [2, p. 357].

Claim: Haise, 107:31:51: "…we found, in the interim of time around the backside there, a little slicker way of doing this."

Status: Confirmed

Word for word in the NASA voice transcript [2, p. 362]. The clip starts partway into Haise's sentence, which begins "Okay, Al. The - the reason for the - some changes I'm ... to feed you up on the procedure is".

Claim: Mitchell, 107:34:22: "…we want to ENTER VERB 21 NOUN 1; 101 ENTER; 107 ENTER." Haise, 107:34:38: "Antares, Houston. Correction on your readback. It's VERB 21 NOUN 01 ENTER; 10 10 ENTER; 107 ENTER." Mitchell, 107:34:54: "Roger; got you. 10 10 ENTER; 107 ENTER." Haise, 107:35:01: "Okay, that's correct."

Status: Confirmed

All four lines are in the NASA voice transcript [2, pp. 362-363] and the mission commentary [3, 306/2]. Mitchell's first line is trimmed; it begins "Okay, Fred, I understand. After P63 is NOUN 9 - NOUN 62. At about 4 minutes" [2, p. 362]. The transcript times put seven seconds between Mitchell's "107 ENTER" and Haise's "Okay, that's correct".

Claim: Fred Haise was the CapCom reading the list up.

Status: Confirmed

The mission commentary named Haise as CapCom for the shift that ran through the landing [3, 287/3 and 316/2]. Mitchell answers the read-ups with "Understand, Fredo" (106:38:15) and "Okay, Fred, I understand" (107:34:22) [2, pp. 358, 362]. The Lunar Surface Journal gives these lines to Haise [6].

Sources

  1. Apollo 14 Mission Report, MSC-04112, NASA Manned Spacecraft Center (May 1971). Text also at the Apollo Lunar Surface Journal.
  2. Apollo 14 Technical Air-to-Ground Voice Transcription, NASA Manned Spacecraft Center (1971). Pages are the transcript's printed page numbers.
  3. Apollo 14 Mission Commentary, NASA Public Affairs Office transcript (1971). Cited by tape and page.
  4. S. Drake, LM Hybrid Simulator Support of the Apollo 14 Mission, DG Memo 1702, MIT Charles Stark Draper Laboratory (17 February 1971)
  5. LM Timeline Book, page 5, annotated scan, Apollo Lunar Surface Journal
  6. Eric M. Jones (ed.), "Landing at Fra Mauro", Apollo Lunar Surface Journal, with audio by Thomas Schwagmeier
  7. "Read-back or Hear-back", SKYbrary Aviation Safety (2026)
  8. Airservices Australia, Safety Net: Communicating with ATC (June 2023)