41 CFR § 301-11.20
May my agency authorize a rest period for me while I am traveling?
June 9, 2020
(a) Your agency may authorize a rest period not in excess of 24 hours at either an intermediate point or at your destination if:
(1) Either your origin or destination point is OCONUS;
(2) Your scheduled flight time, including stopovers, exceeds 14 hours;
(3) Travel is by a direct or usually traveled route; and
(4) Travel is by coach-class.
(b) When a rest stop is authorized the applicable per diem rate is the rate for the rest stop location.
[FTR Amdt. 70, 63 FR 15961, Apr. 1, 1998, as amended by FTR Amdt. 2005-03, 70 FR 28460, May 18, 2005]