Why we all were wrong about operational attrition

[timtom]

ORIGINAL: el cid again

But a typical unit would fly its planes twice a day - 6000 sortees - and tactical planes might be able to sustain 3 flights a day - a rate of 9000 sortees a month. To lose 10 planes out of 6000 is BOTH 10% of a force of 100 planes AND 0.16% per sortee: between one and two tenths of one per cent. And that is HIGH. Often it will be LESS than that.

FWIW, here's some numbers from three of my old UV AAR's (Allied/Japanese):
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8/42-10/42

Air Losses:

Total: 541/568 = 1.00:1.05

Week 1: 8/22 = 1.00:2.75
Week 2: 25/29 = 1.00:1.16
Week 3: 3/5 = 1.00:1.67
Week 4: 90/141 = 1.00:1.57
Week 5: 165/75 = 2.20:1.00
Week 6: 23/46 = 1.00:2.00
Week 7: 16/21 = 1.00:1.31
Week 8: 31/28 = 1.11:1.00
Week 9: 59/56 = 1.05:1.00
Week 10: 67/48 = 1.40:1.00
Week 11: 22/27 = 1.00:1.23
Week 12: 28/53 = 1.00:1.89
Week 13: 4/17 = 1.00:4.25

Air-to-Air: 379/209 = 1.81:1.00
Destroyed on Field: 8/55 = 1.00:6.88
Destroyed by AAA: 83/58 = 1.43:1.00
Operational Losses: 71/246 = 1.00:3.46

Sorties Flown:

Total: 45,726/49,150 = 1.00:1.07

Week 1: 2,329/1,123 = 2.07:1.00
Week 2: 3,630/2,381 = 1.52:1.00
Week 3: 2,673/3,581 = 1.00:1.34
Week 4: 4,374/3,512 = 1.25:1.00
Week 5: 4,806/4,385 = 1.10:1.00
Week 6: 2,558/3,764 = 1.00:1.47
Week 7: 3,272/4,714 = 1.00:1.44
Week 8: 4,910/4,135 = 1.18:1.00
Week 9: 3,962/3,464 = 1.14:1.00
Week 10: 2,670/4,228 = 1.00:1.58
Week 11: 3,913/5,035 = 1.00:1.29
Week 12: 4,092/4,222 = 1.00:1.03
Week 13: 2,538/4,602 = 1.00:1.81

Loss pr. sortie (excl. DoF): 0.0117/0.0104 = 1.1250:1.0000

Operational loss pr. sortie: 0.0016/0.0050 = 1.0000:3.1250
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10/42-12/42

Air Losses:

Total: 1,193/803 = 1.49:1.00

Week 1: 73/46 = 1.59:1.00
Week 2: 27/30 = 1.00:1.11
Week 3: 26/28 = 1.00:1.08
Week 4: 153/121 = 1.26:1.00
Week 5: 159/74 = 2.15:1.00
Week 6: 85/62 = 1.37:1.00
Week 7: 170/114 = 1.49:1.00
Week 8: 83/73 = 1.14:1.00
Week 9: 80/61 = 1.31:1.00
Week 10: 39/17 = 2.29:1.00
Week 11: 37/25 = 1.48:1.00
Week 12: 183/90 = 2.03:1.00
Week 13+1 day: 79/62 = 1.27:1.00

Air-to-Air: 552/320 = 1.73:1.00
Destroyed on Field: 97/85 = 1.14:1.00
Destroyed by AAA: 218/77 = 2.83:1.00
Operational Losses: 326/321 = 1.02:1.00

Sorties Flown:

Total: 58,028/62,493 = 1.00:1.08

Week 1: 3,181/3,487 = 1.00:1.09
Week 2: 4,225/5,128 = 1.00:1.21
Week 3: 3,947/6,296 = 1.00:1.60
Week 4: 4,458/6,454 = 1.00:1.45
Week 5: 4,942/4,183 = 1.18:1.00
Week 6: 4,964/3,504 = 1.42:1.00
Week 7: 4,860/4,146 = 1.17:1.00
Week 8: 3,286/4,129 = 1.00:1.26
Week 9: 4,864/6,000 = 1.00:1.23
Week 10: 3,941/3,498 = 1.13:1.00
Week 11: 3,447/3,729 = 1.08:1.00
Week 12: 6,154/7,376 = 1.00:1.10
Week 13+1 day: 5,751/4,563 = 1.26:1.00

Loss pr. sortie (excl. DoF): 0.0189/0.0115 = 1.6435:1.0000

Operational loss pr. sortie: 0.0056/0.0051 = 1.0980:1.0000
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2/43-4/43

Air Losses:

Total: 759/673 = 1.13:1.00

Week 1: 31/32 = 1.00:1.03
Week 2: 62/63 = 1.00:1.02
Week 3: 43/66 = 1.00:1.53
Week 4: 135/68 = 1.98:1.00
Week 5: 59/63 = 1.00:1.07
Week 6: 40/36 = 1.11:1.00
Week 7: 33/67 = 1.00:2.03
Week 8: 61/49 = 1.24:1.00
Week 9: 64/49 = 1.31:1.00
Week 10: 50/24 = 2.08:1.00
Week 11: 69/55 = 1.25:1.00
Week 12: 55/47 = 1.17:1.00
Week 13: 61/55 = 1.11:1.00

Air-to-Air: 213/214 = 1.00:1.00
Destroyed on Field: 61/76 = 1.25:1.00
Destroyed by AAA: 161/31 = 5.19:1.00
Operational Losses: 324/352 = 1.00:1.09

Sorties Flown:

Total: 86,588/63,200 = 1.37:1.00

Week 1: 4,527/5,021 = 1.00:1.11
Week 2: 5,379/4,800 = 1.12:1.00
Week 3: 6,018/3,832 = 1.57:1.00
Week 4: 6,391/5,355 = 1.19:1.00
Week 5: 5,984/4,862 = 1.23:1.00
Week 6: 6,700/4,565 = 1.47:1.00
Week 7: 5,815/5,605 = 1.04:1.00
Week 8: 6,965/3,737 = 1.86:1.00
Week 9: 7,499/5,909 = 1.30:1.00
Week 10: 7,563/4,862 = 1.56:1.00
Week 11: 7,124/4,354 = 1.64:1.00
Week 12: 8,003/4,802 = 1.67:1.00
Week 13: 8,584/5,486 = 1.56:1.00

Loss pr. sortie (excl. DoF): 0.0081/0.0095 = 1.0000:1.1728

Operational loss pr. sortie: 0.0037/0.0056 = 1.0000:1.5135
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[joliverlay]

I like your numbers.

In an eariler thread I said:

"I'd guess the operational loss rate per sortie must have been around 0.1% to 1% (0.1 to 1 per hundred sorties) and the risk of being shot down was near 1%"

Your loss rate in the UV game looks to be right at 0.5% (0.005) per sortie, right in the middle of my estimate above. The range of values in various UV years was 0.2 to 0.6%. Again I think this is right on target.

Also based on the claim noted above that operational losses were something like 25% of all losses (and 90% in the far north), you can't explain real world losses without having something like 0.1-1% operational losses. If Allied pilots were suffing about 1% loss rate per sorte after 10 missions (and 7% on their first one), as claimed in Victory in the Pacific, than after 10 missions 0.25% losses per sortie would be for operational reasons and 0.75% per sortie would be for combat losses.

If a pilot only had to fly 40 missions, than they would most ofen survive the tour, even with a 1% overall loss rate, keeping in mind that not all losses resulted in loss of the pilot. If all aircraft losses killed the pilot the survival rate would be 67%, if half the aircraft losses were survived that jumps up quite abit, to about 80%. In reality most of the losses in the average come from the new guys and some of the really good pilots keep flying a long time before their luck runs out.