Table S3.

Robustness logistic regression models predicting onboard incidents

VariableModel 1Model 2Model 3
Dependent variableEconomy class incidentEconomy class incidentFirst class incident
DatasetAll flightsFlights with first classFlights with first class
Predictor variables
 Economy seats1.0008 (0.0012)1.0034** (0.0015)
 First class seats1.0389*** (0.0152)
 Economy seat width (cm)0.9542* (0.0230)1.2755** (0.0928)
 Economy seat pitch (cm)0.9874 (0.0100)1.0120 (0.0128)
 First class seat width (cm)0.8014 (0.1095)
 Flight distance in miles1.0004**** (0.0000)1.0004**** (0.0001)1.0003** (0.0002)
 Flight delay (h)1.1450**** (0.0167)1.1324**** (0.0174)1.0263 (0.0556)
 Cabin area (m2)1.1282*** (0.0522)1.1298** (0.0602)1.5079*** (0.2090)
 International (1 = yes)0.6348 **** (0.0679)0.6321**** (0.0736)0.6985 (0.1682)
 First class present (1 = yes)4.0358**** (0.4860)
 Boarding from front (1 = yes)2.3452*** (0.6018)14.5774*** (14.9644)
 Departure time (hours since midnight)1.0610**** (0.0108)1.0555**** (0.0113)1.0719**** (0.0174)
 Flight frequency1.0000 (0.0000)0.9999** (0.0000)0.9999 (0.0001)
Month (April base category)
 August0.7926** (0.0936)0.7856** (0.0959)0.8886 (0.2329)
 December0.7004*** (0.0873)0.6772*** (0.0899)0.7176 (0.2120)
 February0.7985* (0.0963)0.7899* (0.0998)1.3023 (0.3466)
 January0.9545 (0.1060)0.9552 (0.1104)0.7830 (0.1973)
 July0.8626 (0.0936)0.8311 (0.0940)0.7973 (0.2373)
 June1.0048 (0.1045)0.9678 (0.1053)1.0626 (0.3235)
 March0.8410 (0.0955)0.8274 (0.0981)1.1010 (0.3162)
 May0.8737 (0.0928)0.8737 (0.0942)1.3086 (0.3785)
 November0.9916 (0.1345)0.9484 (0.1394)1.1489 (0.2955)
 October0.8826 (0.1034)0.8466 (0.1046)0.8678 (0.2486)
 September0.8073 (0.0991)0.7895* (0.1005)0.5751 (0.2080)
Day of week (Friday base category)
 Monday1.1156 (0.0947)1.0852 (0.0956)1.1615 (0.2278)
 Saturday0.9791 (0.0851)0.9246 (0.0847)1.0270 (0.2346)
 Sunday0.8935 (0.0831)0.8771 (0.0847)1.0171* (0.2239)
 Thursday0.9819 (0.0917)0.9391 (0.0932)1.1982 (0.2734)
 Tuesday0.9835 (0.0828)0.9529 (0.0840)0.8530 (0.2079)
 Wednesday1.1212 (0.1025)1.1259 (0.1076)0.9695 (0.1967)
Departure region–Arrival region (North East Asia–North America base category)
 Western Europe–North America2.7185*** (0.7986)2.3992*** (0.6798)2.2256 (1.4225)
 Caribbean–Caribbean
 Caribbean–North America4.3515**** (1.6960)2.6477** (1.0756)1.3763 (1.2952)
 Central America–North America5.0667**** (1.9621)3.0136*** (1.2487)2.7034 (2.3901)
 Lower South America–Lower South America4.5467*** (2.5514)3.1730** (1.7454)1.4500 (1.8677)
 Lower South America–North America1.6300 (0.6397)1.5842 (0.6269)0.5646 (0.2442)
 Upper South America–North America2.1686 (1.0466)1.6923 (0.8105)3.0285 (2.8611)
 Middle East–North America1.6573** (0.3753)1.6140** (0.3628)2.3261** (0.9126)
 North America–North East Asia1.1166 (0.2305)1.0902 (0.2263)1.3890 (0.5479)
 North America–Western Europe1.5173 (0.4418)1.3800 (0.3893)1.2410 (0.7806)
 North America–Caribbean4.3375**** (1.7686)2.5632** (1.1050)3.1779 (2.9010)
 North America–Central America4.3579**** (1.7757)2.5610** (1.1041)1.2651 (1.3415)
 North America–Lower South America0.8515 (0.1796)0.8302 (0.1696)0.2969 (0.2746)
 North America–Upper South America3.5670*** (1.4991)2.7456*** (1.0720)
 North America–Middle East1.7707*** (0.3936)1.7261*** (0.3786)1.8967* (0.7141)
 North America–North America2.5737** (0.9614)1.6259 (0.6388)1.3173 (1.1065)
 North America–Southwest Pacific0.3888**** (0.0597)0.3661**** (0.0592)0.8155 (0.1967)
 Southwest Pacific–North America0.9666 (0.1519)0.8753 (0.1456)1.6312* (0.4083)
McFadden’s pseudo R20.10800.06300.0758
  • Values presented are odds ratios with robust SEs. The full dataset represented ∼150–300 unique arrival and departure airports, and between 500 and 1,000 unique flight routes. SEs are adjusted clusters based on plane route (i.e., the specific departure airport and arrival airport combination). All models include fixed effects for flight regions. Observations were dropped because they were in a flight region that had no incidents. Flights with first class present are ∼46.1% of the population of flights. No flights without first class boarded from the middle of the plane. *P < 0.10, **P < 0.05, ***P < 0.01, ****P < 0.0001.

  • Seat pitch data are not available because many first class seats had their own pods/beds.