Appellants Ute Harriss and Margaret Feather brought this class action against Pan American World Airways charging it with violations of sections 703(a)(1), (2) of Title VII of the Civil Rights Act of 1964, 42 U.S.C. § 2000e-2(a)(l), (2). They sued on behalf of themselves and other Pan Am female flight attendants. They contend that Pam Am violated Title VII by: (1) requiring that female flight attendants take maternity leave immediately upon learning of their pregnancy; (2) requiring that they not return to work before sixty days after the birth of the child; (3) denying them accrual of seniority after the first ninety days of their leave; and (4) denying them the use of sick leave and other fringe benefits during their leave.
The United States District Court for the Northern District of California, after trial, held that Pan Am’s policies requiring commencement of leave upon pregnancy (Stop Policy) and continuation of leave for sixty days after birth (Start Policy) constituted prima facie sex discrimination but that both policies were justified as business necessities and bona fide occupational qualifications. Harriss v. Pan American World Airways, Inc., 437 F.Supp. 413 (N.D.Cal.1977). The district court held that neither the seniority policy nor the sick leave policy constituted a prima facie violation. Id.1 The class action plaintiffs have not challenged the sick leave holding but are appealing the violation of the Stop and Start Policies and the Seniority Policy.
We agree with the district court that the Stop Policy, although prima facie sex discrimination, was justified by safety considerations. The court did not make sufficient factual findings to allow us to determine the necessity of the Start Policy, and thus we remand that question for further proceedings as herein defined. Finally, we hold that the Seniority Policy constituted prima facie sex discrimination and remand for the district court to determine whether Pan Am established that its policy was justified as either a business necessity or a *673bona fide occupation qualification. We affirm in part and remand in part.
FACTS
The challenged Pan Am maternity leave policy requires a flight attendant to notify her supervisor within twenty-four hours of becoming aware of her pregnancy and, upon giving such notice, to begin immediately an unpaid leave of absence which lasts no fewer than sixty and no more than ninety days after delivery. The policy’s enforcement provision states: “A Cabin Attendant’s failure to comply with any of the procedures set forth above will be considered a voluntary resignation.”
During pregnancy leave, a flight attendant does not accrue seniority and loses certain other employment benefits such as sick pay and some medical insurance coverage. Pan Am classifies pregnancy leave, like medical and emergency leave, as a non-discretionaiy leave of absence. Discretionary leave is granted by Pan Am for personal reasons. Employees on discretionary leave accrue seniority for a maximum of ninety days while those on medical leave may accrue seniority for as long as three years. Feather and Harriss lost approximately 130 days of seniority as a result of their mandatory maternity leaves.
DISCUSSION
The plaintiffs’ Title VII challenge was tried and decided before the amended definition of sex discrimination became effective on October 31, 1978. Under that definition sex discrimination specifically includes discrimination based on pregnancy. Since appellants seek both injunctive relief and back pay, we must assess the legality of Pan Am’s policies both before and after the 1978 amendment.
To establish a Title VII violation for sex discrimination, a plaintiff must carry the burden of proving either that the challenged employment practice intentionally discriminates on the basis of sex or that it has a sexually discriminatory effect. Dothard v. Rawlinson, 433 U.S. 321, 329, 97 S.Ct. 2720, 2726-2727, 53 L.Ed.2d 786 (1977); deLaurier v. San Diego Unified School Dist., 588 F.2d 674, 676 (9th Cir. 1978). If a prima facie case is established, the burden shifts to the employer to justify the challenged practice. Griggs v. Duke Power Co., 401 U.S. 424, 432, 91 S.Ct. 849, 854, 28 L.Ed.2d 158 (1971); deLaurier v. San Diego Unified School Dist., supra. If the employer meets this burden, the plaintiff may show that the employer could use alternative practices which accomplish the same purpose without discriminatory effects. Albemarle Paper Co. v. Moody, 422 U.S. 405, 425, 95 S.Ct. 2362, 2375, 45 L.Ed.2d 280 (1975); deLaurier v. San Diego Unified School Dist., supra.
I. The Pre-Amendment Legality of Pan Am’s Stop Policy
A. Prima Facie Sex Discrimination
The Supreme Court, in General Electric Co. v. Gilbert, 429 U.S. 125, 97 S.Ct. 401, 50 L.Ed.2d 343 (1976), held that an employer’s disability insurance program which excluded coverage for pregnancy-caused disability did not, on its face, constitute sex discrimination under Title VII. In Nashville Gas Co. v. Satty, 434 U.S. 136, 98 S.Ct. 347, 54 L.Ed.2d 356 (1977), however, the Court made clear that pregnancy classifications which had a discriminatory impact on women were prima facie Title VII violations under the reasoning of Griggs v. Duke Power Co., supra (holding that the use of educational prerequisites and intelligence tests was prima facie race discrimination because of the discriminatory effect it had on Blacks). The district court, here, applied Griggs and concluded that Pan Am’s mandatory pregnancy leave policy had a discriminatory impact on women because it had “the effect of excluding a disproportionate number of women from employment.” 437 F.Supp. at 431. We agree.
In deLaurier v. San Diego Unified School Dist., 588 F.2d 674 (9th Cir. 1978), we found that a mandatory pregnancy leave policy for San Diego school teachers had a discriminatory impact on women. We noted that “it is plain that mandatory maternity leave is not the withholding of a potential benefit [as in Gilbert, supra], but is a re*674striction on pregnant women’s employment opportunities.” Id. at 677. Adopting the logic of deLaurier, we agree with the district court’s finding that Pan Am’s Stop Policy had a discriminatory impact on women and was, therefore, a prima facie Title VII violation.
B. The “Business Necessity” Defense
The district court held that Pan Am carried its burden of showing that its Stop Policy was a “Business Necessity” and a “Bona Fide Occupational Qualification” (BFOQ). 437 F.Supp. at 432-35. Plaintiffs challenge this holding on the ground that the district court applied a too lenient standard. Consequently, we must determine the correct standard for these two defenses which we have previously recognized as being closely related. deLaurier v. San Diego Unified School Dist., 588 F.2d at 678.
The district court treated the two defenses interchangeably. In our view, however, the defenses apply to different types of Title VII violations. The BFOQ defense is applicable to employment practices that purposefully discriminate on the basis of sex while the Business Necessity defense is appropriately raised where facially neutral employment practices run afoul of Title VII only because of their disparate impact.2 See Burwell v. Eastern Air Lines, Inc., 24 Empl.Prac.Dec. (CCH) ¶ 31,213, at 17,378-79, 633 F.2d 361 (4th Cir. 1980).
In assessing the legality of employment practices which preceded the 1978 expansion of the definition of sex discrimination, we are compelled by the Supreme Court’s reasoning in Gilbert to treat the Stop Policy as gender-neutral on its face. The district court, therefore, should have considered only whether Pan Am carried its burden of showing Business Necessity.
The standard applied by the district court combined phraseology associated with both the BFOQ and the Business Necessity defenses.3 Even if the district court applied an improper standard, however, we conclude that its findings of fact establish that Pan Am’s Stop Policy was justified as a Business Necessity.
Our most thorough consideration of the Business Necessity defense arose in the con*675text of a challenge to the hiring practices of the Los Angeles Police Department. Blake v. City of Los Angeles, 595 F.2d 1367 (9th Cir. 1979). We found those practices to have a discriminatory impact on women, thus constituting a prima facie Title VII violation. In assessing the City’s assertion of the Business Necessity defense, we quoted the standard accepted by the Supreme Court in Dothard v. Rawlinson, 433 U.S. 321, 332 n.14, 97 S.Ct. 2720, 2728 n.14, 53 L.Ed.2d 786 (1977): “[A] discriminatory employment practice must be shown to be necessary to safe and efficient job performance.” Blake, supra, at 1376. We stated further that, to meet the requirement,
“the business purpose must be sufficiently compelling to override any [discriminatory] impact; the challenged practice must effectively carry out the business purpose it is alleged to serve; and there must be available no acceptable alternative policies or practices which would better accomplish the business purpose advanced, or accomplish it equally well with a lesser [discriminatory] impact.”
Blake, supra, at 1376, quoting from Robinson v. Lorillard Corp., 444 F.2d 791, 798 (4th Cir. 1971).
The district court found that passenger safety was the primary justifying business purpose and that such safety was an essential aspect of Pan Am’s business. Passenger safety is a “sufficiently compelling” purpose to satisfy the first part of the Robinson v. Lorillard test. The district court also found that Pan Am had shown that assessing the abilities of pregnant flight attendants on an individual basis was “highly impractical,” 437 F.Supp. at 435, and that appellants had not established any “feasible alternate policy of lesser adverse impact.” 437 F.Supp. at 434. These factual findings are not “clearly erroneous.”
The district court did not, however, specifically determine the degree of the Stop Policy’s effectiveness in furthering passenger safety. The court found that flight attendants play an important role in certain safety operations, particularly emergency evacuations. 437 F.Supp. at 420-22. The court found further that there was medical evidence to support the view that a pregnant flight attendant, during her first two trimesters, was more likely than a nonpregnant flight attendant to be incapacitated during an emergency evacuation. 437 F.Supp. at 423. The court concluded that, in light of this medical evidence, the Stop Policy was “reasonably calculated to further the safety objective.” 437 F.Supp. at 434. Rather than requiring Pan Am to show that its policy was effective in furthering passenger safety, as required by the Lorillard standard, the district court’s standard required only that the challenged practice be “reasonable” in light of the safety considerations.
The requirement that the challenged policy be “effective” in furthering the asserted business interest is not independent of the requirement that the interest be compelling. The degree of effectiveness required of the Stop Policy depends on the gravity of the safety hazard posed by a flight attendant who becomes incapacitated during an emergency.4
The district court found that 1) “[t]he ability of each flight attendant to perform at full capacity is vital to emergency management”; 2) a flight attendant’s ability to perform her emergency functions might be impaired by fatigue, nausea and vomiting, or spontaneous abortion, all of which occur with some regularity during the first two trimesters of pregnancy; and 3) the gravity of the safety risk, measured by the likelihood of harm and the probable severity of harm, was great enough to warrant the imposition of a stringent personnel policy for flight attendants. None of these findings is clearly erroneous.
*676In light of these findings, we conclude that Pan Am has shown a sufficient correlation between its Stop Policy and passenger safety to satisfy an appropriately narrow standard for the Business Necessity defense.
II. The Post-Amendment Legality of Pan Am’s Stop Policy
A. Prima Facie Sex Discrimination
The Title VII definition of sex discrimination was amended in 1978 to read:
The terms “because of sex” or “on the basis of sex” include, but are not limited to, because of or on the basis of pregnancy, childbirth, or related medical conditions; and women affected by pregnancy, childbirth, or related medical conditions shall be treated the same for all employment-related purposes, ... as other persons not so affected but similar in their ability or inability to work.
42 U.S.C. § 2000e(k) (Supp. II 1978). The legislative history, as well as the statutory language itself, make clear that after October 31, 1978, “distinctions based on pregnancy are per se violations of Title VII.” H.R. Rep. No. 948, 95th Cong., 2d Sess. 3, reprinted in [1978] U.S. Code Cong. & Ad. News, pp. 4749, 4751. Pan Am’s Stop Policy is based on pregnancy and thus, since October 31, 1978, it constitutes per se sex discrimination.
B. The Bona Fide Occupational Qualification Defense
In view of the Stop Policy’s status as per se sex discrimination, Pan Am’s justifications must be evaluated in terms of the BFOQ, rather than the Business Necessity defense. See ante at 1301. The two defenses, though related and similar, are not identical. deLaurier v. San Diego Unified School District, 588 F.2d at 678. They must be distinctly applied. Cf. Burwell v. Eastern Air Lines, Inc., 24 Empl.Prac.Dec. (CCH) ¶ 31,213, at 17,379 & n.15, 633 F.2d 361 (4th Cir. 1980) (suggesting that a policy justified by business necessity may not constitute a BFOQ); but cf. Burwell, 458 F.Supp. 474, 496 n.11 (E.D.Va.1978) (“As a practical matter, however, the Court sees little difference between the two tests.”), aff’d in part, rev’d in part and remanded, 24 Empl.Prac.Dec. (CCH) ¶ 31,213, 633 F.2d 361 (4th Cir. 1980).
We join the Fourth Circuit in adopting the BFOQ standard which the Fifth Circuit developed in Usery v. Tamiami Trail Tours, Inc., 531 F.2d 224 (5th Cir. 1976); Diaz v. Pan American World Airways, Inc., 442 F.2d 385 (5th Cir. 1971); and Weeks v. Southern Bell Telephone & Telegraph Co., 408 F.2d 228 (5th Cir. 1969). Arritt v. Grisell, 567 F.2d 1267, 1271 (4th Cir. 1977).
According to the court’s reasoning in Tamiami,
Diaz mandates that the job qualifications which the employer invokes to justify his discrimination must be reasonably necessary to the essence of his business .... The greater the safety factor, measured by the likelihood of harm and the probable severity of that harm in case of an accident, the more stringent may be the job qualifications designed to insure safe driving.
Tamiami, supra at 236. (Emphasis in original.)
The second facet of the test was enunciated in Weeks, supra at 235.
[A]n employer has the burden of proving that he had reasonable cause to believe, that is, a factual basis for believing, that all or substantially all women would be unable to perform safely and efficiently the duties of the job involved.
However, if the employer cannot make this latter showing, it can nonetheless justify a “reasonable general rule” by establishing “that it is impossible or highly impractical to deal with women on an individualized basis.” Id. at 235 n.5.
The district court specifically found that passenger safety was the essence of Pan Am’s business. 437 F.Supp. at 434. It also found that Pan Am had satisfied the Weeks facet of the test by showing that “it is ‘highly impractical to deal with [pregnant flight attendants] on an individualized ba*677sis’ and it has applied a ‘reasonable general rule.’ ” 437 F.Supp. at 435; cf. Burwell v. Eastern Air Lines, Inc., 24 Empl.Prac.Dec. (CCH) ¶ 31,213, at 17,377 & n.6, 633 F.2d 631 (4th Cir. 1980) (holding “trial court clearly wrong in its finding that pregnant flight attendants who will experience abnormal health incidents during their pregnancies can be uniformly identified prior to the onset of such incidents”). The flaw in the district court’s standard as it applies to the BFOQ defense is that it requires only that the policy be “reasonable” in light of the safety factor rather than “reasonably necessary.” The district court may have reasoned that the safety factor was so significant that any policy which was “reasonably calculated” to further safety was also “reasonably necessary” in light of Pan Am’s strict safety obligations to the public.
Adoption of such a standard here would unnecessarily broaden the BFOQ defense which the Supreme Court characterized in Dothard v. Rawlinson, 433 U.S. 321, 334, 97 S.Ct. 2720, 2729, 53 L.Ed.2d 786 (1977), as “an extremely narrow exception to the general prohibition of discrimination on the basis of sex.” In light of the district court’s factual findings regarding the significance of the safety risk involved in allowing pregnant flight attendants to continue flying, 435 F.Supp. at 420-23 & nn. 10-15, we conclude that Pan Am has shown its Stop Policy to be “reasonably necessary” to passenger safety.
Accordingly, we affirm the district court’s decision that Pan Am’s Stop Policy was justified as a BFOQ.5
III. Pre-Amendment Legality of Pan Am’s Start Policy
A. Prima Facie Sex Discrimination
Pan Am’s Start Policy (requiring female flight attendants to wait at least sixty days after delivery to resume their duties), as much as its Stop Policy, is “a restriction on pregnant women’s employment opportunities.” deLaurier v. San Diego Unified School Dist., 588 F.2d 674, 677 (9th Cir. 1978). Consequently, it has a discriminatory impact on women and is a prima facie violation of Title VII.
B. Business Necessity Defense
The district court noted that the justification for the Start Policy “did not receive extensive attention at trial.” 437 F.Supp. at 424. The court referred to the testimony of two doctors who felt that the postpartum medical examination should be delayed until six weeks or more after delivery. Id. A doctor testified on behalf of plaintiffs that he preferred an individualized policy but that he could “see an argument” for putting off the examination until four to six weeks after delivery. Id. The record can be read to support a finding that flight safety requires that flight attendants refrain from work until passing a postpartum examination. While there is no evidence that all women must wait until after the postpartum examination to return to work, the very point of the examination is to assess the risk of disabilities-particularly that of postpartum hemorrhaging. At trial, two doctors testified that until six weeks uterine size and body functions do not sufficiently normalize to permit a reliable judgment on whether a woman is ready to return to work. Until that time, all women risk disability. Pan Am elects to counter that risk with a generalized stop policy. We find no error in that procedure.
The district court made no findings about the gravity of the risk to passenger safety of allowing flight attendants to return to work before sixty days after birth, nor did it conclude that Pan Am’s Start Policy was necessary in light of that risk. It did not explain why a sixty day period was justified when Pan Am’s doctors referred to an examination at six weeks. The mere fact that Pan Am’s experts testified that a postpartum examination should occur after “six weeks or more” does not preclude a finding that a sixty day start policy is justified. *678The district court may have believed that medical uncertainty and deference to the complexity of Pan Am’s “ultimate chore of managing risks to passengers,” Burwell v. Eastern Air Lines, Inc., 24 Empl.Prac.Dec. (CCH) ¶ 31,213, at 17,379, 633 F.2d 361 (4th Cir. 1980), required it to find that a sixty day start period is justified, even though expert testimony indicated a somewhat shorter period. Accordingly, we remand for a determination of whether Pan Am carried its burden of showing that its sixty day rule was justified as a Business Necessity.
IV. Post-Amendment Legality of Pan Am’s Start Policy
A. Prima Facie Sex Discrimination
The 1978 Amendment incorporating pregnancy discrimination into Title VIPs definition of sex discrimination makes Pan Am’s Start Policy facial sex discrimination.
B. Bona Fide Occupational Qualification Defense
The district court did not make sufficient findings for us to decide whether Pan Am’s Start Policy was a BFOQ. We remand for the court to make this determination under the Weeks-Diaz test outlined above.
V. Pre-Amendment Legality of Pan Am’s Seniority Accrual Policy
A. Prima Facie Sex Discrimination
The district court held that the Supreme Court’s analysis in General Electric Co. v. Gilbert, 429 U.S. 125, 97 S.Ct. 401, 50 L.Ed.2d 343 (1976) foreclosed Plaintiffs’ contention that Pan Am’s policy of denying seniority accrual during maternity leaves constituted prima facie sex discrimination under Title VII. 437 F.Supp. at 437. The district court issued a Supplemental Memorandum reaffirming its decision on the Seniority Policy in light of the Supreme Court’s intervening opinion in Nashville Gas Company v. Satty, 434 U.S. 136, 98 S.Ct. 347, 54 L.Ed.2d 356 (1977).
In Satty, the employer required pregnant employees to take a formal leave of absence during which they forfeited their accrued seniority. When an employee returned after such leave, she could get only those positions which no other employee with seniority had requested. The court held that the policy burdened women in a way that men were not burdened and thus that it violated section 703(a)(2) of Title VII. Id. at 139-40, 98 S.Ct. at 349-350. The Satty Court distinguished Gilbert as involving solely the refusal to confer a benefit which men could not obtain. Such a denial of a benefit, as opposed to the imposition of a burden, did not have the effect of depriving women of employment opportunities and thus did not violate section 703(a)(1).
In contrast to the policy challenged in Satty, Pan Am’s policy does not deprive women of their accumulated seniority, but merely denies continued accrual beyond the first ninety days of maternity leave. The district court, in its Supplemental Memorandum Opinion, noted that seniority is generally earned only for work done. The court concluded that Pan Am’s seniority policy is more akin to the denial of a benefit than the imposition of a burden and, therefore, does not constitute a prima facie Title VII violation. 441 F.Supp. at 883. We disagree.
The Court in Satty attached considerable weight to the EEOC guidelines dealing with seniority accrual during maternity leave. 434 U.S. at 142 n.4, 98 S.Ct. at 351 n.4. Those guidelines specify that “employment policies and practices involving . .. the accrual of seniority ... shall be applied to disability due to pregnancy or childbirth on the same terms and conditions as they are applied to other temporary disabilities.” Id. quoting 29 CFR § 1604.10(b) (1976). Pan Am has established that pregnant flight attendants are sufficiently disabled from performing their emergency safety operations to justify mandatory maternity leave despite its discriminatory impact. Other types of medical or disability leave allow seniority accrual for up to three years. Maternity leave allows only ninety days.
Mr. Justice Stevens, in his concurring opinion in Satty, suggested a practical way *679to distinguish policies which impose burdens, as in Satty, from those which merely deny benefits, as in Gilbert. 434 U.S. at 153-57, 98 S.Ct. at 357-359. He suggested that when “the employer has a policy which adversely affects a woman beyond the term of her pregnancy leave,” the employer has imposed a burden. Id. at 155, 98 S.Ct. at 358. The named plaintiffs Margaret Feather and Ute Harriss lost approximately 130 days of seniority. Such lapses in seniority may cause losses of 20 to 40 positions on the seniority roster. 437 F.Supp. at 417. A flight attendant who returns from maternity leave will feel the effects of her lowered position on the seniority roster for the remainder of her employment with Pan Am. Because the plaintiffs lost seniority in relation to those fellow employees who were not required to go on maternity leave, or who took other types of medical or disability leave, plaintiffs’ ability to obtain desired positions and working conditions was hampered. We conclude, therefore, that Pan Am’s Seniority Policy constituted prima facie sex discrimination.
B. Business Necessity
Because the district court concluded that the Seniority Policy did not have a discriminatory effect on women, it did not reach the question of a Business Necessity justification. Pan Am had the burden of showing that denial of seniority accrual was “necessary to safe and efficient job performance.” Dothard v. Rawlinson, 433 U.S. 321, 332 n.14, 97 S.Ct. 2720, 2728 n.14, 53 L.Ed.2d 786 (1977). We remand to the district court to decide, (from the record,) whether Pan Am carried its burden.
VI. Post-Amendment Legality of Pan Am’s Seniority Accrual Policy
Like Pan Am’s Stop and Start Policies, the Seniority Policy is expressly based on pregnancy which, after the 1978 amendment, makes the Seniority Policy facial sex discrimination. We remand the question of the post-amendment legality of the Seniority Policy for a determination from the record of whether Pan Am carried its burden of justifying its policy as a Bona Fide Occupational Qualification.
Affirmed in part, reversed in part, and remanded.
. The district court, in a Supplemental Memorandum, reaffirmed its Seniority Policy holding in light of the Supreme Court’s intervening decision in Nashville Gas Company v. Satty, 434 U.S. 136, 98 S.Ct. 347, 54 L.Ed.2d 356 (1977). Harriss v. Pan American World Airways, Inc., 441 F.Supp. 881 (N.D.Cal.1977).
. The BFOQ defense is contained in the statute itself and provides that “it shall not be an unlawful employment practice for an employer to ... employ employees ... on the basis of his ... sex ... in those instances where ... sex ... is a bona fide occupational qualification reasonably necessary to the normal operation of that particular business.” 42 U.S.C. § 2000e-2(e). The Business Necessity defense, by contrast, has no specific basis in Title VII, having evolved primarily from Griggs v. Duke Power Company, 401 U.S. 424, 91 S.Ct. 849, 28 L.Ed.2d 158 (1971) as a defense to claims that facially neutral employment practices have discriminatory effects. When a facially neutral practice is challenged for its disparate impact, the employer’s justification is not that “sex . . . is a bona fide occupational qualification” but that the practice is not based on sex at all but on some nondiscriminatory business purpose. The Fifth Circuit expressly adopted this interpretation in Garcia v. Gloor, 609 F.2d 156, 163 (5th Cir. 1980):
Both the BFOQ and BND [Business Necessity Defense] are defenses but a BFOQ is a warrant for affirmative deliberate discrimination while a BND is a defense to the prima facie case made when an apparently neutral employment practice is shown to have a discriminatory effect.
This distinction may also be reasonably inferred from the Supreme Court’s analysis in Dothard v. Rawlinson, 433 U.S. 321, 97 S.Ct. 2720, 53 L.Ed.2d 786 (1977) which involved a Title VII challenge to one employment policy based expressly on sex and another which was facially neutral but which had a disparate impact on women. The Court considered only the BFOQ defense in assessing the legality of the facially discriminatory policy and only the Business Necessity Defense for the facially neutral policy.
. The district court required Pan Am to show that its Stop Policy was “necessary to the safe and efficient operation of a business.” 437 F.Supp. at 432. This is the typical standard for the Business Necessity defense. See, e.g., Dothard v. Rawlinson, 433 U.S. 321, 332 n.14, 97 S.Ct. 2720, 2728 n.14, 53 L.Ed.2d 786 (1977) and Robinson v. Lorillard Corp., 444 F.2d 791, 798 (4th Cir. 1971). In enumerating the elements of the required showing, however, the district court employed the standard for the BFOQ defense developed by the Fifth Circuit. See Usery v. Tamiami Trail Tours, Inc., 531 F.2d 224 (5th Cir. 1976). 437 F.Supp. at 432-33.
. The Tenth Circuit acknowledged this in applying the Business Necessity defense. Spurlock v. United Airlines, 475 F.2d 216 (10th Cir. 1976). Federal courts have uniformly recognized the relevance of the safety factor in assessing whether an employment policy is justified as a BFOQ. Arritt v. Grisell, 567 F.2d 1267 (4th Cir. 1977); Usery v. Tamiami Trail Tours, Inc., 531 F.2d 224 (5th Cir. 1976); Hodgson v. Greyhound Lines, 499 F.2d 859 (7th Cir. 1974).
. At oral argument, Appellants abandoned their contention that Pan Am’s avowed concern about pregnant flight attendants’ physical ability was merely a pretext concealing a discriminatory intent. Consequently, we do not consider that issue here.