U.S. DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION RECEIVED 

FEDERAL AVIATION 

ADMINISTRATION 

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AUG 2 1 2015 

Complainant, Docket No. 2012NM0650~j=ARING DOCKET 

FDMS No. FAA-2013-0292 

v. 

SKYWEST AIRLINES 

Respondent. 

COMPLAINANT'S APPEAL BRIEF 

Pursuant to section 13.233(d) of the Rules of Practice, 14 C.F.R. § 13.233(d), Complainant files this 

brief in support of its appeal of the Initial Decision issued by Administrative Law Judge Richard C. 

Goodwin (ALJ) on May 29, 2015, in the above-captioned matter. 

I. STATEMENT OF THE CASE 

On June 19,2012, Complainant issued a Final Notice of Proposed Civil Penalty alleging that 

Sky West Airlines ("Sky West" or "Respondent") took off civil aircraft N426SW, a Bombardier CL-600-

2B19, when frost was present on the aircraft's upper wing surface, contrary to SkyWest's Operations 

Specifications (OpSpecs) and in violation of 14 C.F.R. §§ 119.5(g) & (1), 121.629(b), and 91.13(a). 

Respondent timely requested a hearing and the matter was heard before Administrative Law Judge (ALJ) 

Richard C. Goodwin on February 10-11 & 19,2014. In the Initial Decision issued on May 29, 2015, ALJ 

Goodwin found that Complainant had failed to establish a primafacie case supporting the above-listed 

violations and dismissed the Complaint with prejudice. Complainant timely appealed this decision. 

II. STATEMENT OF THE FACTS 

On December 7, 2011, Aaron Perkins, an FAA Aviation Safety Inspector, arrived at Salt Lake City 

International Airport (SLC) at approximately 7:00A.M. to conduct a routine de-ice inspection. (Tr. 27). 

Upon arrival, he observed two Sky West CRJ aircraft undergo de-icing procedures (Tr. 28), and described 

the weather as a cold, clear morning, with light winds, conducive to frost formation. (Tr. 27 & 73). At 

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approximately 7:41 A.M., Inspector Perkins observed Sky West aircraft N426SW at gate Echo I preparing 

for pushback and departure. (Tr. 29). To get a closer inspection of the aircraft, he parked his vehicle and 

approached N426SW. I d. At this point, he observed frost on the upper surface of the left wing. (Tr. 29). 

He then returned to his vehicle, moved it around to the west side of the airplane, and inspected the right 

wing of the aircraft, where he also observed frost. (Tr. 30). Inspector Perkins performed a tactile inspection 

on one portion of the wing by running his hand over the area where frost was present. (Tr. 32). From this 

visual and tactile inspection, he estimated the frost on the wing was at least as thick, if not thicker, than a 

sheet of paper. (Tr. 33). Standing behind the right wing, approximately three feet to the left of the wing tip 

(Tr. 55), Inspector Perkins photographed the frost on the wing using his iPhone. (Tr. 30 & 77; Ex. A-3). 

He also took a photograph of the aircraft's tail number. (Tr. 55). He returned to his vehicle, expecting to 

follow N426SW to the de-ice pad so that he could observe the de-icing process. (Tr. 34). Instead, he 

watched N426SW push back, taxi, and take off without performing any de-icing procedures. (Tr. 36-37). 

Meteorological records from the National Climactic Data Center show that at 14:53 Zulu (7:53 

A.M. local), which is approximately 15 minutes before N426SW took off, the temperature at SLC was 

minus 7 degrees Celsius (or approximately 19.4 degrees Fahrenheit). (Ex. A-5 at 2). 1 Thomas Bond, 

FAA's chief scientist and technical advisor for flight environmental icing (Tr. 180), who was qualified as 

an expert in aircraft icing (Tr. 194), testified that the weather conditions at this time were conducive to frost 

formation. (Tr. 198). Specifically, the atmospheric conditions on December 7, 2011, including the dew 

point and temperature, and the potential for radiational cooling, lead him to conclude that frost could have 

indeed formed on the wing ofN426S W. (Tr. 198-199). He also concluded, based on Inspector Perkins's 

testimony and the photograph ofN426SW's wing (Ex. A-3), that the contamination witnessed and 

photographed by Inspector Perkins on December 7, 2011, was indeed frost. (Tr. 200). 

Yet, the First Officer ofN426SW's Flight 7770, Dennis Burr, completed a pre-flight inspection of 

the aircraft approximately 15-20 minutes prior to Inspector Perkins's inspection and did not see any frost. 

1 Respondent's expert, Kevin Perry, also testified that at 7:40A.M. it was actually colder, at a temperature of negative 

8 degrees Celsius (17.6 degrees Fahrenheit). (Tr. 508). 

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(Tr. 303, 319). Additionally, Daniel Anderson, a Sky West Captain seated as a passenger in 6B of Flight 

7770, also testified that he looked out the window ofN426SW at approximately 7:40 and did not observe 

frost on the left wing. (Tr. 397-99). This discrepancy- between Inspector Perkins's inspection and the 

testimony of Respondent's witnesses- is reconciled by Respondent's own expert in atmospheric sciences, 

Kevin Perry. Specifically, Dr. Perry explained that the likely triggering event for the formation of the frost 

was the addition of cold fuel, which occurred after the First Officer's walk around. (Tr. 513-17). Indeed, 

Dr. Perry testified that the wing would quickly adopt the temperature of the cold fuel pumped into it. 

(Tr. 517). This event, taken in conjunction with the temperature decrease from negative 7 to negative 

8 degrees Celsius over the relevant time period, produced conditions conducive to frost formation on the 

wing ofN426SW after the First Officer Burr completed his cold weather inspection, but prior to Inspector 

Perkins's discovery of the frost. (See Tr. 518). 

Sky West's OpSpecs authorized the use of Ground Deicing Program Manual SP 2800 (Ex. A-2; 

Answ. ~ 4), which prohibits Sky West from taking off an aircraft when frost is present on an upper wing 

surface. (Answ. ~ 5). When frost is present on an aircraft, Sky West's Manual requires the contamination to 

be removed by the de-icing process prior to takeoff. (Ex. A-2; Tr. 65). Respondent admits that the weather 

conditions on the ground prior to N426SW's departure were conducive to the formation of frost on the 

aircraft's wings. (Resp't Resp. to Reg. for Admis. No. 1 ). Respondent also admits that N426SW did not 

receive an application of de-icing fluid during the time that it was on the ground at SLC prior to takeoff. 

(Resp't Resp. to Reg. for Admis. No.2; see Tr. 264-273). Moreover, none of Respondent's witnesses 

testified that they viewed or examined the wing following Inspector Perkins's discovery and photographing 

of the frost. 

Respondent's defense, therefore, rested on its expert, Dr. Perry, who testified that, using an estimate 

of the amount of frost that could have formed on N426SW's wing (Tr. 525- 29), a combination of factors 

including ambient air temperature, radiant energy, reflectivity of the aircraft's wing, and available sunlight 

would have sublimated the frost prior to the aircraft's takeoff at 8:08A.M. (Tr. 535-37). Essentially, 

Dr. Perry used an assumption of the amount of frost present at N426SW's 7:51 A.M. push back from the 

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gate (Tr. 525-528) and an approximation of the amount of atmospheric energy available during its taxi time 

to opine that it was unlikely that the frost witnessed by Inspector Perkins was still present when the aircraft 

took off. (Tr. 541). In rebuttal to this opinion, Complainant's witness Roy Rasmussen, an expert in 

aviation weather with a Ph.D. in atmospheric science (Tr. 627-30, 634), testified that Dr. Perry's 

calculations, and thus his conclusions relating to the amount of energy available for and energy required for 

sublimation, were incorrect. (See Tr. 644-652). Specifically, Dr. Rasmussen testified that Dr. Perry 

calculated the amount of energy necessary to sublimate frost that was 0.05 millimeters thick, rather than the 

0.1 millimeter (paper-thick) frost testified to and photographed by Inspector Perkins; thus, the actual 

amount of energy sufficient to sublimate the frost present on N426SW's wing would be double the amount 

calculated by Dr. Perry. (Tr. 641-42). Additionally, Dr. Rasmussen opined that the heat balance equation 

Dr. Perry used to calculate the amount of energy available to sublimate the frost was incorrect; Dr. Perry 

overestimated both the amount of radiation available from the atmosphere (Tr. 650) and the amount of 

radiation emitted by N426SW's wing (Tr. 645-48), such that, even adjusting for zero solar radiation (i.e., 

night time conditions when frost should be prevalent), frost would not form (Tr. 644). 

In his initial decision, the ALJ summarized each witness' testimony and found "the testimony of all 

witnesses to have been truthful and credible." (Initial Decision at 18). He also found the testimony of each 

expert witness to be informative and instructive, but determined that they "ultimately rebutted each other." 

IQ, Deciding in favor of Respondent, the ALJ found that the FAA had failed to carry its burden of proof. 

!d. at 19. Specifically, the AU determined that the FAA failed to make a prima facie case that Respondent 

took offN426SW with frost present on its wing in violation of 14 C.F.R. §§ 119.5(g) & (l), 121.629(b), and 

91.13(a). Id. On these grounds, the ALJ dismissed FAA's Complaint with prejudice. 

lll. STATEMENT OF THE ISSUE 

Whether Complainant Met its Burden of Establishing by a Preponderance of 

the Evidence that Sky West Took OffN426SW When Frost was Present on 

the Aircraft's Upper Wing Surface in Violation of I 4 C.F.R. §§ 119.5(g) 

& (!), 121.629(b), and 91.13(a). 

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IV. STANDARD OF REVIEW 

Under the Rules of Practice, the Administrator considers on appeal whether the ALJ' s findings of 

fact are supported by a preponderance of reliable, probative, and substantial evidence. 14 C.F.R. 

§ 13.233(b)(l). The Administrator also considers whether the ALI's conclusions oflaw are in accordance 

with applicable law, precedent, and public policy. 14 C.F.R. §13.233(b)(2). Finally, the Administrator 

considers whether the ALJ committed prejudicial errors during the hearing or proceedings. 14 C.F.R. 

§ 13.233(b)(3). In civil penalty proceedings, the burden of proof is, in the first instance, on the 

Complainant. See 14 C.F.R. § 13.224(a). The Administrator has held that Complainant may sustain this 

burden of proof through the use of circumstantial evidence. In the Matter of Custom Aviation, Inc., FAA 

Order No. 2005-1,2005 WL 916047, at *6 (Mar. 8, 2005) (citing In the Matter ofCont'l Airlines, Inc., 

FAA Order No. 90-12 at 16 (April25, 1990)), Once Complainant has established a prima facie case, the 

burden of production shifts to Respondent who must rebut Complainant's evidence. In the Matter of Eric 

W. Hereth, FAA Order No. 95-26, 1995 WL 853896, at *7 (Dec. 19, 1995)). TfRespondent fails to 

overcome Complainant's prima facie case, a preponderance ofthe evidence establishes a violation. See In 

the Matter of Am. W. Airlines, FAA Order No. 96-3, 1996 WL 210094, at *13 (Feb. 13, 1996). On appeal, 

the Administrator may reweigh the evidence presented at hearing to determine whether each party has met 

its respective burden. Custom Aviation, Inc., FAA Order No. 2005-1, at *6-7. 

V. ARGUMENT 

A. Complainant Met its Burden of Establishing by a Preponderance of the Evidence that Sky West 

Took OffN426SW When Frost was Present on the Aircraft's Upper Wing Surface in Violation of 

14 C.F.R. §§ 119.5(g) & (1), 121.629(b), and 91.13(a). 

Complainant has the burden of proving a violation of the Federal Aviation Regulations (FARs) by a 

preponderance of the evidence. 14 C.F.R. § 13.233(b ). To meet this burden, Complainant must first present 

a prima facie case, see Hereth, FAA Order No. 95-26, 1995 WL 853896, at *7, demonstrating that it is 

more probable than not that a violation of the FARs occurred. In the Matter ofCont'l Airlines, Inc., FAA 

Order No.98-6, 1998 WL 231441, at *2 (Mar. 10, 1998). If a Respondent fails to rebut Complainant's 

prima facie case, Complainant has met its burden of proving a violation by a preponderance of the 

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evidence. See Am. W. Airlines, FAA Order No. 96-3, 1996 WL 210094, at *13. Here, Complainant 

introduced evidence sufficient to support a reasonable inference, and thereby, a prima facie case, that 

N426SW took off with frost present on the upper surface of the aircraft's wings. For reasons discussed 

below, Respondent failed to rebut this prima facie case, and, therefore, a preponderance of the reliable, 

probative, and substantial evidence supports a finding that Sky West violated 14 C.F.R. §§ 119.5(g) & (1), 

121.629(b), and 91.13(a). 

I. Complainant Established a Prima Facie Case that Respondent Took OffN426SW with Frost 

Present on the Upper Surface of the Aircraft's Wing. 

To meet its burden, Complainant must demonstrate that it is more likely than not that Respondent 

took offN426S W with frost present on its wing. Tellabs. Inc. v. Makor Issues & Rights, Ltd., 551 U.S. 

308, 328-29 (2007) ("preponderance of the evidence" standard, stated otherwise, is "more likely than not"). 

Direct evidence establishing the frost's presence at takeoff, however, is not required. Cont'l Airlines, Inc., 

FAA Order No.98-6, 1998 WL 231441, at *3 (fmding the ALJ erred by requiring direct evidence to sustain 

burden of proof). It is well-established that Complainant can use circumstantial evidence to sustain its 

burden of proof. In the Matter of Florida Propeller & Accessories, Inc., FAA Order No. 97-32, 1997 WL 

685987, at *3 (Oct. 7, 1997) ("Complainant may use circumstantial evidence to sustain its burden of 

proof."); In the Matter of Hampton Air Transp. Sys., Inc., FAA Order No. 97-11, 1997 WL 93231, at *I 

(Feb. 19, 1997). Applied here, Complainant has met its burden of establishing a prima facie case if it 

presented evidence- circwnstantial or otherwise- sufficient to support a "reasonable inference" that frost 

was present at takeoff. See Hereth, FAA Order No. 95-26, 1995 WL 853896, at *7. 

Complainant has met this burden. Inspector Perkins, an Aviation Safety Inspector and former 

airline pilot (Tr. 23-24), testified that he observed frost on the upper portion of both the left and right wings 

ofN426SW right before the plane began to push back from the gate, which was at approximately 7:52 

A.M. (Tr. 29-30; Ex. A-6). He performed a tactile inspection on the portion of the wing where frost was 

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present by running his hand over the area. (Tr. 31-32)." From this inspection, he estimated that the frost on 

N426SW's right wing was at least as thick, if not thicker, than a sheet of paper. (Tr. 33). After performing 

this inspection, he photographed the frost and the aircraft's tail number. (Tr. 33, 55; Ex. A-3 & A-4). 

Thomas Bond, an expert in aircraft icing who has worked in the field since 1986, first at NASA and now at 

the FAA (Tr. 181-84), also reviewed Inspector Perkins's photograph and concluded that the photograph 

depicted frost on N426SW' swing. (Tr. 200). He further testified that the weather conditions on that 

morning were conducive to frost, given the dew point and temperature, and the fact that radiational cooling 

could induce a lower temperature on the wing. (Tr. 199). Respondent does not dispute this fact, (See Resp't 

Resp. to Req. for Adrnis. No. 1), and even Respondent's own expert concluded that the weather and 

N426S W's wing conditions were "enough to permit the formation of a tenuous layer of frost during the 

inspection period." (Ex. R-4 at 5). 

Accordingly, the preponderance of reliable, probative evidence demonstrates that frost existed on 

the upper surface ofN426SW's wing during Inspector Perkins's inspection. None of Respondent's fact 

witnesses- First Officer Burr, Captain Gibbs, or Captain Anderson- testified that they observed the 

aircraft's wings cifter Inspector Perkins discovered frost. Indeed, Captain Gibbs did not leave the cockpit or 

perform a pre-flight ice inspection of aircraft (Tr. 261, 282); Captain Anderson, a passenger on flight 7770, 

viewed only a portion of the left wing from his seat in 6b around 7:40A.M. (Tr. 394-398); and First Officer 

Burr testified that he performed a pre-flight inspection' of the wings about ten to 15 minutes after the 

aircraft arrived in SLC (Tr. 319), which was around 7:10 to 7:20 in the morning.4 (Tr. 322; Ex. A-6). First 

Officer Burr left the cockpit once more to check the aircraft's fuel door (Tr. 332-33) around 7:40 to 7:45 

2 Inspector Perkins testified that he is trained in the contaminant detection process, which involves both a visual 

observation and a tactile inspection to verifY the presence of contamination. (Tr. 31 ). Inspector Perkins testified that 

he did not perform a complete inspection, that is, he did not perform a tactile inspection on the forward part ofthe 

wing, but he did do a tactile inspection of the portion of the wing where he saw the frost. (Tr. 32). 

3 First Officer Burr also testified that he did not perform a tactile inspection on the entire portion of the leading edge 

of the wing or the entire length of the upper portion of the wing. (Tr. 330-3 I). 

4 A CARS data shows that Flight 7770 was initialized at 14:23 A.M. (7:23A.M. local), which would put the aircraft's 

arrival into SLC slightly before that time period. First Officer Burr testified that the aircraft would have landed in 

SLC at around 7:10 in the morning. (Tr. 341). 

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(Tr. 262), but his path would not have put him in a position to observe the portion of the wing where frost 

was present (see Tr. 283) and, furthermore, this check again occurred prior to Inspector Perkins's 

observance of the frost. Accordingly, this testimony only suggests that the frost was not present prior to 

Inspector Perkins's inspection. As explained by Dr. Perry, this is because the likely triggering event for the 

formation of the frost was the addition of cold fuel (Tr. 513-17), which would have produced conditions 

conducive to frost formation on the wing ofN426SW after the First Officer completed the cold weather 

inspection, but prior to Inspector Perkins's discovery of the frost. (See Tr. 518). Thus, Inspector Perkins, 

being the person who viewed the condition of the aircraft nearest to its takeoff, provided the most probative 

testimony of the existence of frost during the relevant time period. 

Inspector Perkins's ph0tograph (Ex. A-3) is corroborative of his testimony and is also probative 

evidence of the existence of frost on N426SW's right wing. The ALJ gave little evidentiary weight to this 

photograph (Decision at 18) because Spencer Hyde, a graphic designer for Sky West, testified that the 

metadata from an electronic copy oflnspector Perkins's photograph showed that it was modified at 

8:31 P.M. on the date it was taken. (Tr. 453). Though this modification indicates the file was changed in 

some manner, the witness could not speculate as to how. (Tr. 453). Indeed, he acknowledged that the 

modification time stamp could be related to something as simple as renaming the file or converting the 

photograph from JPEG to PDF format. (Tr. 467-69). In contrast to this speculative testimony, Inspector 

Perkins testified that the photograph fairly and accurately depicted the frost that he observed on the upper 

surface of the right wing ofN426SW on the morning of December 7, 2011. (Tr. 51). He also testified that 

the photograph itself had not been modified since it was captured using his phone. (Tr. 86). The ALI found 

Inspector Perkins's testimony to be truthful and credible. (See Decision at 18). Therefore, the ALl's failure 

to give probative value to Inspector Perkins's photograph is without merit. 

N426SW did not receive an application of de-icing fluid between the time that Inspector Perkins 

photographed and observed the frost and the aircraft's takeoff. (Resp't Resp. to Req. for Admis. No.2; 

Tr. 36-37, 264-270). Given Thomas Bond's testimony the weather conditions that morning, including 

temperature and dew point, were conducive to frost formation (Tr. 198-199), this fact is sufficient to permit 

8 
a "reasonable inference" that that the frost observed by Inspector Perkins at 7:48A.M. was still present at 

N426SW's 8:08A.M. takeoff. See Hereth, FAA Order No. 95-26, !995 WL 853896, at *7 ("Administrator 

was only required to present evidence sufficient to support a reasonable inference that the engine failure 

was due to respondent's fuel mismanagement."); Am. W. Airlines, FAA Order No. 96-3, 1996 WL 210094, 

at * 13 (finding Complainant presented enough evidence in its case-in-chief to raise a "reasonable 

inference" that aircraft no longer conformed to its original type design). 

Despite Respondent's contention to the contrary, the absence of direct evidence that the frost 

photographed by Inspector Perkins still existed at takeoff is not fatal to Complainant's case. See, e.g., 

Cont'l Airlines, Inc., FAA Order No. 98-6, 1998 WL 231441, at *2 (stating that "governing case law 

indicates that direct evidence is not required"). Circumstantial evidence leading to the reasonable inference 

that it was more likely than not that the frost observed by Inspector Perkins existed at N426SW's takeoff is 

sufficient to sustain Complainant's burden of proof. See Proud v. C.A.B., 357 F.2d 221, 224 (7th Cir. 1966) 

(finding that circumstantial evidence creating a "strong inference" of violation sustained Complainant's 

burden ofproofby substantial evidence). Although Respondent contends that an intervening event- i.e., the 

16 minutes between when N426SW began to push back from the gate and the aircraft's 8:08A.M. takeoffnegates a reasonable inference of violation, it is not incumbent upon Complainant to "exclude every 

conceivable possibility of an intervening [event]" in order to meet its burden. ld5 

Respondent's argument that the frost may have sublimated during this time period is properly 

characterized as a defense to Complainant's allegations. Cf. In the Matter ofCont'l Airlines, Inc., FAA 

Order No. 90-18, 1990 WL 656271, at *6-7 (Aug. 22, 1990). Complainant is not required to negate a 

respondent's defense in order to prove a prima facie case. Administrator v. Specht, 25 C.A.B. 859 (April I, 

5 The Respondent in Proud argued that all possibilities that the unairworthy condition of an aircraft originated 

subsequent to his certification of the aircraft as airworthy should have been affirmatively excluded in order to sustain 

Complainant's burden of proof. The court found, however, that Complainant had established a prima facie case 

through circumstantial evidence and was not required to exclude every conceivable possibility of an intervening cause 

in order to meet its burden. Proud, 357 F.2d at 224. 

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1957), affd Specht v. CAB, 254 F.2d 905, 914-15 (8th Cir. 1958).6 Applied here, this premise holds that 

Complainant was not required to disprove the possibility of sublimation in order to carry its burden. Rather, 

once Complainant established a primafacie case of the existence of frost, the burden shifted to Respondent 

to produce rebuttal evidence demonstrating that the frost observed by Inspector Perkins was not still present 

at takeoff. 

2. Respondent Failed To Rebut Complainant's Prima Facie Case. 

Complainant established a prima facie violation of 14 C.P.R.§§ 119.5(g) & (1), 121.629(b), and 

91.13(a), by introducing circumstantial evidence sufficient to support a reasonable inference that 

Respondent took offN426SW with frost present on the upper surface of the aircraft's wings. Once this 

was established, Respondent was obliged to offer evidence in rebuttal. Proud, 357 F.2d at 224; Hereth, 

FAA Order No. 95-26, 1995 WL 853896, at *7. To do so, Respondent introduced the expert testimony 

Dr. Perry, who opined that the frost observed by Inspector Perkins would not have still been present at 

takeoff because it would have sublimated during the intervening minutes between N426SW's pushback and 

its takeoff. (See Tr. 537-541). To counter this testimony, Complainant offered the expert opinion of 

Dr. Rasmussen who testified that an error with Dr. Perry's heat balance equation and several unfounded 

assumptions used to derive his energy calculations invalidated Dr. Perry's conclusion. (See Tr. 639-652). 

Therefore, Respondent failed to overcome Complainant's primafacie case because: (1) Dr. Perry's opinion 

that the frost would have sublimated during N426SW's taxi lacked the logic, depth, and persuasiveness 

sufficient to rebut complainant's evidence; and (2) Respondent failed to rebut Complainant's evidence 

because the ALJ found that Respondents' experts "ultimately rebutted each other." 

6 See In the Matter of High Exposure. Inc., FAA Order No. 2003-7, 2003 WL 22480443, at *6 (Sept. I 0, 2003) 

(Complainant not required to disprove Respondent's argument that records of AD compliance could exist at other 

maintenance shops in order to demonstrate an aircraft was unairworthy). See also Gullatte v. Potts, 654 F.2d 1007, 

1015 (5th Cir. 1981) (tin ding trial court erred by placing burden on plaintiff to disprove a qualified immunity defense, 

rather than simply requiring plaintiff to establish a prima facie case); Jalil v. Avdel Com., 873 F.2d 701, 707 (3d Cir. 

1989) (fmding plaintiff did not have to disprove insubordination~ a defense in employment discrimination action- to 

succeed at the first level of proof, because "it is more logically a defense that is raised at the second level to meet the 

plaintit1's prima facie case of discrimination"). 

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a) Respondent's Expert's Opinion that the Frost Would Have Sublimated During 

N426SW's Taxi Lacks Logic, Depth, and Persuasiveness. 

Expert testimony is not evaluated on the basis of credibility, but on its logic, depth, and 

persuasiveness. In the Matter of Valley Air Servs., Inc., FAA Order No. 96-15, 1996 WL 336051, at *3 

(May 3, 1996).7 Here, Respondent's rebuttal to Complainant'sprimafacie case rests on Dr. Perry's expert 

testimony that the frost would have sublimated prior to takeoff; constructing a heat balance equation, 

Dr. Perry testified that the amount of energy available for sublimation was greater than the energy 

necessary to completely sublimate the amount offrost present on N426SW's wings. (See Tr. 524- 541). 

Yet, as explained by Dr. Rasmussen, an expert in aviation weather who holds a Ph.D. in atmospheric 

science (Tr. 627 -30), to reach this unsound conclusion Dr. Perry: (I) overestimates the amount of radiation 

from the atmosphere that was available for sublimation; (2) relies on a generous speculation as to how long 

N426SW was in sunlight; and (3) uses an unsubstantiated frost thickness to calculate the amount of energy 

required for sublimation. (See Tr. 634-652). Therefore, Dr. Perry's opinion lacks the logic, depth, and 

persuasiveness necessary to rebut complainant's primafacie case of violation. 

1. Dr. Perry Overestimates the Amount of Radiation from the Atmosphere that 

was Available for Sublimation. 

To support his opinion that the frost would have sublimated, Dr. Perry used a heat balance equation 

to divine N426SW's wing's heating/cooling rate, and in tum, used this rate to determine how much energy 

would be required to sublimate the frost present on the aircraft's wing. (Ex. R-4 at 5). This heat balance 

equation is comprised of several terms, including the absorption of infrared energy from the atmosphere, 

the absorption of solar radiation, and the emission of infrared energy from the wing to the atmosphere. 

(Ex. R-4 at 5). Dr. Perry derived two of these terms, specifically the absorption of infrared energy from the 

atmosphere and the emission of infrared energy from the wing, from the Stephan-Boltzman Law, which 

calculates the amount of energy emitted by an object. (Ex. R-4 at 4-6). 

7 Findings of the ALJ based on the testimony of expert witnesses do not deserve the deference accorded to an AU's 

factual findings based upon his assessment of witness credibility. In the Matter of Griffin Avionics, Inc., FAA 2007-

9,2007 WL 3159418, at *5 (Aug. 2, 2007). 

11 
However, as explained by Dr. Rasmussen, the Stephan-Boltzman equation specifically calculates 

the radiation emitted from a black body object. (Tr. 645). A black object radiates efficiently. (Tr. 645). But 

neither the atmosphere nor N426SW's wing are black objects; therefore, they do not radiate as efficiently 

as the Stephan-Boltzman Law calculates. (Tr. 646-47). What is missing from Dr. Perry's equations, thus, is 

an emissivity factor that would compensate for this phenomenon. (Tr. 646). Therefore, as explained by 

Dr. Rasmussen, both of Dr. Perry's tenns for the absorption of infrared energy from the atmosphere and the 

emission of infrared energy from the wing are too high; each should have been multiplied by a reduction 

factor to account for the decreased emissivity rate of a non-black object. (Tr. 646-4 7). 

In particular, Dr. Perry vastly overestimated the first term in his heat balance equation, the 

absorption of infrared energy from the atmosphere, which represents the amount of infrared heating that is 

coming from the sky. (Tr. 643). Dr. Perry's calculations presume that the air radiates as a black body. 

(Tr. 649). But the air, comprised primarily of oxygen and nitrogen, does not. (Tr. 649). This 

overestimation is apparent, Dr. Rasmussen explains, because even adjusting the heat balance equation to 

zero solar radiation, which is equivalent to night time conditions without any sunlight, frost would not have 

formed given Dr. Perry's calculations. (Tr. 644). But it was these overestimated terms that Dr. Perry used 

to calculate the amount of energy available to sublimate the frost. (Ex. R-4 at 4-7). Thus, the actual energy 

available from the atmosphere is significantly less than that which Dr. Perry calculated, rendering his 

ultimate conclusion that there existed enough energy to sublimate the frost on N426SW's wing invalid. 

(Tr. 652). 

n. Dr. Perry's Conclusion Relies on a Generous Speculation as to How Long 

N426SW was in Sunlight. 

To determine whether there existed enough energy to sublimate the frost present on N426SW's 

wing, Dr. Perry multiplied the wing's heating/cooling rate, which he derived from his heat balance 

equation, by the amount of time in minutes that N426SW was exposed to atmospheric and solar radiation. 

(Ex. R-4 at 5-7). This heat balance equation accounts for a constant amount of solar radiation (specifically, 

8.3 W m"2

), approximated using sunlight measured at 8:00A.M. on December 7, 2011 at a point 20 miles 

12 
north of SLC. (Ex. R-4 at 5, 7). The wing's calculated heating rate, therefore, presumes a constant rate of 

sunlight. Once he calculated this heating rate, he multiplied this term by 17 minutes (Ex. R-4 at 7)- which 

is the amount of time between the point at which N426SW's wheels began moving and the aircraft took off. 

Therefore, Dr. Perry's ultimate conclusion that there was 21,318 joules of energy available for frost 

sublimation presumes that N426SW was exposed to 17 minutes of constant sunlight. (See Ex. R-4 at 7). 

The evidence, however, does not establish that N426SW was necessarily in sunlight for 17 minutes. 

It can be concluded from the Aircraft Communications Addressing and Reporting System (A CARS) that 

the aircraft began to push back at 7:52A.M., which is the point at which the aircraft's tires began rolling. 

(Ex. A-6; Tr. 280). But this pushback movement is slow; the aircraft's departure from the gate is not done 

under its own power, but rather through the use of a tug. (Tr. 271, 280). It took the aircraft six minutes in 

total to push back before the brake was set again at 7:58A.M. (Ex. A-6; Tr. 288). When N426SW began its 

pushback, it was parked in the shadow of the terminal building and was not exposed to sunlight. (Tr. 115, 

170). But once it pushed back, it would have been in sunlight. (Tr. 117). It is not possible, however, to 

determine at what point during this six minute movement N426SW emerged from the shadow cast by the 

terminal building. Nor is it possible to know if the aircraft was moving at a uniform speed during this 

push back movement; A CARS data does not show distance, just time. (See Ex. A-6). There is no way to tell 

from the A CARS data or the testimony in the record where, physically, along N426SW's pushback path the 

aircraft was at any given moment. 8 By way of illustration, it is just as conceivable that the aircraft moved 

ten inches backwards in the first five minutes as it is that the aircraft moved ten feet. 

Thus, the only logically sound conclusion that can be drawn from this data is that the aircraft 

entered sunlight at some point between when the wheels began moving at 7:52A.M. and when they 

stopped at 7:58A.M. (Ex. A-6; 286-89). Because the aircraft took off at 8:08A.M., it can be inferred that 

N426SW was in sunlight for a length of time anywhere between ten to 16 minutes. Decreasing the length of 

time N426SW was exposed to sunlight decreases the amount of energy available for sublimation. By way 

of illustration, ifN426SW remained in the terminal building's shadow for five of the total six pushback 

8 Captain Gibbs testified simply that it was a standard pushback and exit. (Tr. 272-73, 277). 

13 
minutes, this would leave only I 1 minutes of solar and atmospheric radiation available for sublimation at 

the levels calculated by Dr. Perry. Substituting 11 minutes (in place of Dr. Perry's assumed 17), ceteris 

paribus, yields an available amount of energy for sublimation of just 13,794 joules. (See Ex. R-4 at 7: 

20.9 W m·

2 

x II minutes x 60 seconds= 13,794 J m·2 of energy). This is less than the 14,250 joules of 

energy Dr. Perry calculated would be necessary to sublimate the frost completely prior to N426SW's 

takeoff. (Ex. R-4 at 7). Accordingly, Dr. Perry's assumption that there existed enough energy available for 

complete frost sublimation relies on an unsubstantiated assumption about the amount of solar radiation to 

which N426SW was exposed. 

Ill. Dr. Perry Uses an Unsubstantiated Frost Thickness to Calculate the Amount of 

Energy Required for Sublimation. 

Even using Dr. Perry's overestimation of atmospheric radiation and his speculative estimate of 

N426SW's sunlight exposure, his calculations using his heat balance equation do not prove that the frost on 

N426SW's wing would have sublimated by the time the aircraft took off. This is because Dr. Perry bases 

his estimate of how much energy would be required to sublimate the frost on N426SW's wing on an 

assumption of the maximum amount of frost, i.e., the thickness, that could have possibly formed during the 

relevant time period. (Tr. 527). To do so, he used a chart derived from a mathematical model created by 

NASA that modeled frost formation on airfoil in four different ambient conditions. (Tr. 526). Using this 

chart, he selected an ambient condition that "most closely corresponds" to the ambient conditions at SLC 

on December 7, 2011, and used these conditions to estimate an "upper bound" for the growth of the frost. 

(Tr. 526-27). From these assumed conditions, he determined that the maximum thickness of the frost 

"would have been about half the thickness of a piece of paper" or about 0.05 millimeters. (Tr. 528-29, 561 ). 

Dr. Perry then used this rough estimate of thickness to calculate the amount of energy that would be 

required to completely sublimate the frost, arriving at 14,250 joules of energy per meter squared. (Tr. 535). 

Accordingly, Dr. Perry's conclusion about how much energy would be required to sublimate the 

frost on N426SW's wing is entirely reliant on the thickness of the frost. (Tr. 559). Indeed, Dr. Perry 

characterizes the thickness as "a key ingredient in the calculation." (Tr. 559). But Dr. Perry's estimate is 

14 
purely speculative, and has only a tenuous relationship to the evidence developed at hearing and the actual 

conditions that existed at SLC on December 7, 2011. On cross-examination, Dr. Perry admitted that he did 

not input the actual atmospheric conditions that existed at SLC into the mathematical formula derived by 

NASA; instead, he approximated the thiclmess by using a chart consisting of set of hypothetical ambient 

conditions. (Tr. 570-72). Although he suggests that these hypothetical conditions were the "closest analog" 

(Ex. R-4 at 7) to the meteorological conditions observed at SLC, even Dr. Perry testified that the 

hypothetical conditions from which he drew his conclusion used both a different temperature and different 

amount of moisture in the air from those which actually existed at on December 7, 2011. (Tr. 526, 571). 

In contrast to this speculative assumption, Inspector Perkins, who actually viewed, observed, and 

touched the frost in question, testified that the frost was as thick as, if not thicker than, a piece of paper. 

(Tr. 31-33). This is double the amount of frost that Dr. Perry used in his estimation. (Tr. 641 ). 

Dr. Rasmussen and Dr. Perry both agree that if the amount of frost on N426SW's wing was greater than 

Dr. Perry's assumption, the amount of energy that would be required to sublimate it would be greater as 

well. (See Tr. 561, 641-42). In fact, doubling the thickness of the frost would have the effect of doubling 

the amount of energy required to eliminate that frost. (Tr. 642). 

Therefore, even presuming, arguendo, that Dr. Perry's heat balance equation was logical and 

persuasive, it does not prove that the frost would have sublimated. Doubling Dr. Perry's estimate of the 

energy needed for sublimation- which he calculated as 14,250 joules (Tr. 535)- produces a new estimate 

of28,500 joules of energy needed to sublimate the frost on N426SW's wing prior to takeoff. Dr. Perry's 

own heat balance equation, even using his generous sunlight estimation and overestimation of available 

radiation,9 suggests that there would be only 21,318 joules of energy available for sublimation. (Ex. R-4 

at 7). By Dr. Perry's own admission, if the energy required to sublimate the frost was higher than 21,318 

joules per meter squared, some frost would have remained at takeoff. (Tr. 563). Such is the case here: given 

Inspector Perkins testimony that the frost was 0.1 millimeters thick, 28,500 joules of energy- higher than 

the amount of energy Dr. Perry calculated was actually available- would be required to completely 

9 See subparagraphs (a)(i) and (a)(ii) above. 

15 
sublimate the frost. Thus, his conclusion that the frost observed by Inspector Perkins would have 

completely sublimated by the time the aircraft took off is invalid. (See Tr. 641-42, 652). 

For the foregoing reasons, Dr. Perry's expert testimony is insufficient to rebut Complainant's prima 

facie case. Cf. Am. W. Airlines, FAA Order No. 96-3, 1996 WL 210094, at *13 (expert's "confusing and 

often unsubstantiated testimony lacked depth, logic and persuasiveness" and did not "compel a finding that 

America West did not violate Section 43.13(a)"). Because Dr. Perry's testimony is not persuasive on the 

issue of whether N426SW took off with frost on its wing, his opinion does not does not support the ALJ's 

finding; rather, the preponderance of the evidence demonstrates that Respondent violated 

14 C.F.R. §§ 119.5(g) & (1), 121.629(b), and 91.13(a) as alleged in the Complaint. 

b) The ALJ Found that Respondent's and Complainant's Experts "Ultimately Rebutted 

Each Other." Thus, Respondent Failed to Rebut Complainant's Prima Facie Case. 

Even assuming Respondent's expert testimony held the requisite depth and logic necessary to be 

persuasive, his testimony is insufficient to rebut Complainant's prima .facie case. At the conclusion of 

Complainant's case-in-chief, Respondent moved for judgment in its favor seeking dismissal of the 

Complaint. (Tr. 237-42). To grant a motion to dismiss at this stage in the hearing, an ALJ must find that 

Complainant has failed to present a prima .facie case. See, e.g .. Administrator v. Segura, NTSB Order 

No. EA-3848, 1993 WL 87679, at *I (1993). A prima facie case has been made, and consequently a motion 

to dismiss will not be granted, if there is "sufficient proof to support a finding of violation, disregarding 

evidence to the contrary." Administrator v. Kiscaden, NTSB Order EA-3618, 1992 WL 172760 at *3 n.4 

(1992). Here, the ALJ denied Respondent's motion at the hearing and affirmed this ruling in his decision, 

finding that "Complainant had met its initial burden of proof." (Decision at I 0). 

Once Complainant established a prima .facie case, the burden shifted to Respondent to produce 

evidence sufficient to rebut the evidence in Complainant's case-in-chief. Hereth, FAA Order No. 95-26, 

1995 WL 853896, at *7; Am. W. Airlines, FAA Order No. 96-3, 1996 WL 210094, at *13. Here, the ALJ 

found that Dr. Perry's testimony and Dr. Rasmussen's testimony "ultimately rebutted each other." 

(Decision at 18). Accordingly, the ALJ essentially found that Dr. Perry's testimony, and consequently his 

16 
opinion that the frost would have sublimated, was ultimately rebutted by Dr. Rasmussen, Complainant's 

rebuttal witness. (Decision at 18). Absent Dr. Perry's opinion on sublimation, Respondent failed to set 

forth sufficient evidence and testimony to rebut the reasonable inference that it was more probable than not 

that the frost existed at takeoff. When a respondent fails to rebut Complainant's evidence, Complainant has 

met its burden and the preponderance of the evidence supports a finding of violation. Cf. In the Matter of 

High Exposure, Inc., FAA Order No. 2001-2, 200 I WL 629389, at *2 (May 15, 200 I) (ALJ correctly found 

a violation operation once Complainant established a prima facie case of reckless operation and 

Respondent's failed to prove that someone else operated the flight). Here, Respondent's failure to rebut the 

Complainant's primafacie case of the existence of frost at takeoff supports a finding that Respondent took 

offN426SW in violation of 14 C.P.R.§§ 119.5(g) & (1), 121.629(b), and 91.13(a). 

VI. CONCLUSION 

For all of the foregoing reasons, Complainant respectfully requests that the Administrator reverse 

the ALJ' s conclusion that Complainant failed to meet its burden of establishing by a preponderance of the 

evidence that Respondent took off N426SW with frost present on its wing in violation of 14 C.F .R. 

§§ 119.5(g) & (1), 121.629(b), and 91.13(a). 

By: 

Dated: August 21, 2015 

Respectfully submitted, 

Peter J. Lynch 

Assistant Chief Counsel for nforcement 

Casey E. Gardn r, 

Enforcement Di isi 

Federal Aviation Administration 

Office of the Chief Counsel 

800 Independence Ave., S.W. 

Washington, D.C. 20591 

Telephone: (202) 267-5964 

Facsimile: (202) 267-5106 

17 
CERTIFICATE OF SERVICE 

I hereby certify that on this date I have sent the foregoing Complainant's Appeal Brief by U.S. 

certified mail, return receipt requested, postage prepaid, to: 

Todd Emerson, Esq. 

Sky West Airlines, Inc. 

444 South River Road 

St. George, UT 84 790 

In addition, I certify that I have on this date personally delivered the original and one copy ofthe 

foregoing document to: 

Attn: Hearing Docket Clerk, AGC-430 

Wilbur Wright Building- Suite 2WI 000 

Federal Aviation Administration 

600 Independence A venue SW 

Washington, DC 20591 

Dated: August 21, 2015 

18