Please send any factual corrections to tips@aspenflyright org for our prompt attention. We’ll correct our publications as needed, and post a log here. Please tell us whether we may acknowledge your correction or you prefer to remain anonymous.

In Essay #2, endnote 36, line 1, for “2002” read “2022”. Thanks to Barry Vaughan.

Essay #2 was accidentally posted in the incompletely corrected draft “ABL-essay_2.Safety_21-Dec-2022r”. As soon as we realized this, on 25 Jan 2023, it was replaced with the corrected final draft ABL essay_2lSafety_22 Dec 2022r.pdf. We apologize for any confusion.

In Essay #3, “Runway robbery?,” posted 29 December 2022, two errors were marked and corrected in a reposting on 5 January 2023:

Also in Essay #3, on 15 Dec 2023, we changed the revision date on p 1 line 1; on p 8, paragraph 3, line 2, corrected “83/17” to “17/83”; and on p 8, last paragraph, line 1, changed “sufer” to “suffer”.

In Essay #4, p 7, “2022” paragraph, line 3, for “expert leading the preparation of” read “forecaster for”. Also, note 32 should be replaced by this corrected version:

[32] [1] At, starting at 2:33:39. The quoted remark is at 2:34:15. The speaker, William Flock, is listed as “Director” on the Jacobsen | Daniels website, and was identified (at 40:11 of, 20 April 2023 brief to AAB) as “the forecaster” by Jacobsen | Daniels co-owner and ALP / Fleet Mix Study Project Manager Brad Jacobsen. We erroneously attributed the quotation to Mr. Jacobsen and have posted a correction. We did not correct references to “the County’s top aviation technical consultant” that did not name a person, because that consultant is the firm Jacobsen | Daniels. Please see the posted correction under’s “Corrections” tab for additional details.

Mr. Flock did say on 19 October 2022, and we accurately quoted, that “I think everyone on this call here agrees that the CRJ-700 is going to be flying for the next 20 or 30 years, that it’s not going away.” That appears to be a forecast, not a statement of potential. As stated on p 7 of our Essay #4, Mr. Jacobsen now asserts that the statement should have indicated mere capability, not prediction. The 20 April 2023 draft Airport Forecast clearly states another two decades (though it doesn’t go further) as a plausible operating capability for CRJ-700s, which airlines may or may not find it economical to exploit; Jacobsen | Daniels now thinks they probably won’t. That doesn’t change Mr. Flock’s apparent prediction last October. Nothing in the 20 April 2023 draft Forecast indicates any need to change our Essay #4’s facts, logic, or conclusions supporting the prospects of long-term operation of CRJ-700s at Aspen. We now feel even more confident that their risks and uncertainties look lower and more tractable than for the EMB-175LR.

Also in Essay #4, in the fourth-from-last line on p 11, we corrected consultant Alec Seybold’s name (misspelled Alex). We apologize for this error. And on 15 Dec 2023, we deleted the superfluous second “of” (of four) in line 3 of n 28 on p 15, and added the revision date on p 1 line 1.

On 15 Dec 2023, we added a 15 Dec 2023 revision date to Essay #5 (p 1 line 1), and on p 20, line 6, changed “to remain” to “could remain”, although “to” correctly reflects what Bill Flock actually said on videotape, as discussed above with reference to Essay #4.

On 25 Dec 2023, we also corrected in Fig. 8 (p 20) the lower-right-corner red caption to reflect that the potential CRJ700 retirement range shown by the red arrow came not from Brad Jacobsen but from Bill Flock, Pitkin County’s senior aviation forecast author (see Corrections to Essay #4).

On 18 July 2023 in Essay #10, we made these corrections:

  • p 1, line 1: delete superfluous “60” before “Essay” and add at end “revised 15 Dec 2023”
  • p 17, text paragraph 3, line 5, for “of” read “per”
  • p 18, lower table, “Averaging Time,” line 5 (PM2.5), for “1 minute” read “5s”
  • p 25, fourth line below images, delete “PM1, ”
  • p 29, n 27, line 1, the first “PM” in the article title should be “PM10”
  • p 33, n 87, next-to-last line, for “10-15-nm” read “10–15-nm”

On 15 Dec 2023, we corrected:

  • p 11, paragraph 1, in line 2 dehyphenate “upwind” and in line 8 for “UPF” read “UFP”
  • p 27, line 7 after table, after “actual model” add “are valid”; line 9, dehyphenate “corre-lated”

On 5 May 2023, we corrected four small typographic errors in Essay #14 (4 May 2023):

  • p 10, paragraph 3, line 3, for “is” read “are”
  • p 13, paragraph 3, line 3, close up “landing—”
  • p 15, paragraph 2, line 3, close up “planes—”
  • p 15, paragraph 2, line 5, close up “innovation”

On 15 Dec 2023, we changed Essay #14’s revision date (p 1 line 1, replacing the note “(there is no Essay #13)” to 15 Dec 2023, and made these corrections:

  • p 15, we deleted the superfluous hyphen in response #27, line 5, and added at the end of n 2: “In spring 2023, the 23-page document was taken down and replaced by a different web-formatted one at the same URL, as explained in our annotated 12 Dec 2023 op-ed at, p 5, n 17.”
  • p 6 paragraph 3 line 3, and p 9 paragraph 3 line 3, for “E175ER” read “E175LR”.
  • p 10: delete the superfluous “an” between paragraphs 2 and 3, preserving their break.
On 6 April 2024, we corrected notes 13 and 14 in Essay #14, p. 17. In note 13, line 1, the date of Rick Carroll’s Aspen Times article is 13 Sep 2015, not 2021, and we added its URL: “,be%20flying%20the%20Aspen%20skies.” In the following line, for “in autumn 1995” read “by autumn 2015”. We added at the end of note 13: “[Note added 6 April 2024: Jim Crown died in a motorsport accident on 25 June 2023.]”
In note 14, we added the full citation: ‘C. Epstein, “G650 Won’t Spread Its Wings at Aspen Airport,” Aviation International News, 4 June 2012,” and reflected the publisher’s change in the URL, whose “/aviation-international-news/“ changed to “/business-aviation/“.

On 25 June 2023, we posted a corrected version of Essay #15 (so marked in the top line on p. 1). It corrects in red, using strikethroughs and additions, minor errors on pages 8, 13, 17, 17, 18, 21, and 37. None changes the analysis or conclusions.

On 15 December 2023, we corrected Essay #15’s p 4, line 2, and p 6, line 7, from “nearly 6” to “about 5”, and we replaced the graphic at the bottom of p 5 to correct a formula error we discovered in the green data point for 2032 (changing its noise change per plane from 1.60 to 1.18 EPNLdB). In the caption at the top of p 6, line 13, we changed “and noise” to “(plus noise, not comparably graphed because dB are logarithmic rather than linear units)”. We also deleted the superfluous “CRJ700” on p 35, n 18, line 3; added the URL starting in the last line on p 35 (n 18); and updated p 36 line 3 (n 18) from “which merits rechecking” to “later validated for ICAO’s 3 Sep 2021 LL variant (thanks to Bill Tomcich)”. On p 36, we revised the end of n 26 to delete “cannot be validated without knowing the revisions’ source and content” and substituted “apparently come from ICAO’s complex 9 Sep 2022 v2.31 update at”; subsequent page numbers may shift slightly. On p 1 line 1, we updated Essay #15’s revision date to 15 Dec 2023.

On 15 Dec 2023, we corrected our 12 Dec 2023 Aspen Daily News op-ed’s annotated version, p 7, n 28, line 2, to change “2027” to “2032”.