Request for clarification regarding FAR 117.27

FAR 117.27 Consecutive nighttime operations.

A certificate holder may schedule and a flightcrew member may accept up to five consecutive 

flight duty periods that infringe on the window of circadian low if the certificate holder provides 

the flightcrew member with an opportunity to rest in a suitable accommodation during each of 

the consecutive nighttime flight duty periods. 

The rest opportunity must be at least 2 hours, measured from the time that the flightcrew member 

reaches the suitable accommodation, and must comply with the conditions specified in § 

117.15(a), (c), (d), and (e). 

Otherwise, no certificate holder may schedule and no flightcrew member may accept more than 

three consecutive flight duty periods that infringe on the window of circadian low. 

For purposes of this section, any split duty rest that is provided in accordance with § 117.15 

counts as part of a flight duty period.

The problem seems to be with the term infringe on the window of circadian low. 

The ‘conservative’ interpretation would be for any FDP that either Ends within the WOCL, 

Overlaps the WOCL, or Starts within the WOCL, would be considered a nighttime operation.

The ‘liberal’ interpretation would be for any FDP that either Ends within the WOCL or Overlaps 

the WOCL, would be considered a nighttime operation, while a FDP that starts within the 

WOCL or remains entirely free of the WOCL would not be considered a nighttime operation.

The only previous letters of interpretation from the FAA using the term infringe, concerned FAR 

121.471, 1992-Bergner, 2000-Rubin and 2003-Johnson. All dealt with a Duty period that 

infringed upon the start time of the Compensatory rest period.

The attached example shows a trip that would be considered to be in violation of 117.27 if the 

‘conservative’ interpretation is applied, however the same trip would be considered legal if the 

‘liberal’ interpretation is applied.

The ‘liberal’ interpretation seems to follow the language as provided in:

117.21 Reserve status.

(d) For long call reserve, if a certificate holder contacts a flightcrew member to assign him or her to a 

flight duty period that will begin before and operate into the flightcrew member’s window of circadian low, 

the flightcrew member must receive a 12 hour notice of report time from the certificate holder.

Under this section it is very clear, the FDP starts before the WOCL (02:00) and operates beyond 

02:00, thus requiring a 12:00 notice before report.

If the FAA’s interpretation of infringe is to begin before and operate into, then that is acceptable, 

else if the FAA’s interpretation is that in fringe is to overlap any portion, then that would be 

acceptable.
Example of Trip that contains 4 consecutive starts within the WOCL (02:00 – 05:59)

Report 4:40 FDP Limit 10:00 Block Limit 8:00

Day Flight Depart (Base time) Arrive (Base time) Equip Block Grd.

1 Mo 3365 RDU 5:25 PHL 6:41 RJW 1:16 0:53

1 Mo 3972 PHL 7:34 CLE 9:03 RJW 1:29 0:27

1 Mo 3972 CLE 9:30 PHL 10:51 RJW 1:21 0:45

1 Mo 3110 PHL 11:36 PVD 12:44 RJW 1:08 17:06

Release 12:59 Duty 8:19 FDP 8:04 Block 5:14

Rest Period 16:06 Sleep Opp. 15:06

Report 5:05 FDP Limit 12:00 Block Limit 9:00

Day Flight Depart (Base time) Arrive (Base time) Equip Block Grd.

2 Tu 3415 PVD 5:50 PHL 6:56 RJW 1:06 0:39

2 Tu 3329 PHL 7:35 STL 9:00 RJW 1:25 0:45

2 Tu 3344 STL 9:45 PHL 12:55 RJW 3:10 0:44

2 Tu 4033 PHL 13:39 CVG 15:22 RJW 1:43 14:58

Release 15:37 Duty 10:32 FDP 10:17 Block 7:24

Rest Period 13:58 Sleep Opp. 12:58

Report 5:35 FDP Limit 12:00 Block Limit 9:00

Day Flight Depart (Base time) Arrive (Base time) Equip Block Grd.

3 We 6012 CVG 6:20 DCA 7:45 RJW 1:25 1:22

3 We 3442 DCA 9:07 MHT 10:32 RJW 1:25 0:43

3 We 3361 MHT 11:15 DCA 12:50 RJW 1:35 1:18

3 We 6024 DCA 14:08 ISP 15:14 RJW 1:06 14:46

Release 15:29 Duty 9:54 FDP 9:39 Block 5:31

Rest Period 13:46 Sleep Opp. 12:46

Report 5:15 FDP Limit 12:00 Block Limit 9:00

Day Flight Depart (Base time) Arrive (Base time) Equip Block Grd.

4 Th 5019 ISP 6:00 DCA 7:21 RJW 1:21 1:17

4 Th 3794 DCA 8:38 BHM 10:36 RJW 1:58 0:39

4 Th 3794 BHM 11:15 DCA 13:17 RJW 2:02 0:31

4 Th 3889 DCA 13:48 RDU 14:45 RJW 0:57

Release 15:00 Duty 9:45 FDP 9:30 Block 6:18

TAFB 82:20 Duty 38:30 FDP 37:30 Block 24:27
Thank for your attention to this matter.

Respectfully submitted.

Garret Healy

Sr. System Programmer

____________________________________________

Jeppesen Commercial & Military Aviation | New York

Making Every Mission Possible

ph: 212.478.1259 | fax: 212.725.0327 garret.healy@jeppesen.com

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