The determination of the altitude of bodies above the surface of the earth has interested physicists, meteorologists, balloonists, mountain climbers, and aviators. The methods used have been similar and rest on facts which have been well known for a long time. This paper is confined to the theory and methods of the accurate determination of altitude of aircraft above the earth’s surface and brings together all of the well known facts and methods in addition to some new material.
It is here emphasized that for aviation purposes, the altitude is determined by observations of pressure and temperature. A relation of pressure and temperature to altitude is derived. This expression is:
in which h is the altitude in feet, P0 is the atmospheric pressure at the ground level, P is the pressure at the upper level, and tm is the mean temperature of vertical column of air between the two levels.
A more complete expression for the altitude is also derived in which the factors of slight practical importance are included. These factors are those of humidity and gravity.
The observations of pressure and temperature necessary to determine an altitude are discussed. The instruments used to make these observations are briefly described.
The method of computation of the altitude from these observations is outlined and illustrated by a sample computation.
The paper concludes with tables of upper air data, aircraft performance standards and altimeter calibration standards for the United States and other countries.
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Upper Air Observations: Average Yearly for United States
1
2
3
4
5
6
Altitude 1000 ft.
Pressure mm Hg
Temperature °C
Vapor Pressures mm Hg
Density kg/m3
Density Relative to 1.225 kg/m3
0
760.0
19.1
10.54
1.202
0.981
1
736.4
17.1
9.27
1.172
.956
2
710.2
15.1
8.05
1.140
.930
3
685.0
13.1
7.01
1.108
.904
4
659.9
11.7
6.15
1.073
.876
5
637.0
10.4
5.41
1.040
.849
6
614.2
9.3
4.78
1.006
.821
7
592.1
7.5
4.17
0.977
.798
8
570.5
5.7
3.58
.948
.774
9
549.4
3.9
3.07
.919
.750
10
528.3
+ 2.1
2.64
.890
.727
11
507.8
+ 0.2
2.26
.862
.704
12
488.7
− 1.5
1.93
.835
.682
13
469.9
− 3.4
1.65
.808
.660
14
452.1
− 5.4
1.40
.783
.639
15
435.1
− 7.2
1.17
.758
.619
16
418.9
− 9.0
0.99
.736
.601
17
402.3
−11.0
.81
.712
.582
18
387.1
−13.0
.69
.690
.564
19
371.6
−15.0
.56
.668
.545
20
356.1
−17.0
.48
.645
.527
21
341.9
−19.0
.41
.624
.510
22
327.9
−21.1
.33
.605
.494
23
313.9
−23.2
.28
.584
.477
24
301.5
−25.2
.23
.565
.461
25
289.3
−27.2
.20
.546
.446
26
277.4
−29.2
.18
.528
.431
27
265.7
−31.2
.15
.510
.416
28
254.3
−33.1
.13
.492
.402
29
243.6
−35.0
.10
.476
.389
30
233.7
−36.8
.08
.459
.375
31
225
−38.7
.444
.362
32
216
−40.3
.428
.349
33
206
−41.9
.413
.337
34
197
−43.5
.398
.325
35
188
−45.0
.03
.383
.313
36
179
−46.7
.369
.301
37
171
−47.9
.355
.290
38
164
−49.0
.340
.278
39
158
−50.0
.327
.267
40
151
−50.8
.009
.313
.256
45
119
−54.0
.006
.251
.205
50
95
−55.3
.004
.199
.162
Table 2
Upper Air Observations: Means for Canada
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
762.8
9.0
1.258
1
677.3
5.3
1.134
2
598.5
+ 1.8
1.011
3
527.3
− 3.4
0.905
4
463.5
− 8.9
.815
5
407.3
−15.3
.733
6
356.3
−22.1
.662
7
309.8
−29.5
.592
8
268.5
−37.1
.528
9
231.8
−43.7
.470
10
199.5
−49.8
.415
11
171.0
−53.7
.365
12
146.2
−56.8
.314
13
125.2
−59.0
.268
14
106.5
−59.5
.233
15
90.0
−62.0
.198
The observations were made in latitude 43° approximately.
Table 3
Upper Air Observations Mean for S. E. England
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
760.5
9.0
1.253
1
675.1
5.0
1.128
2
596.3
+ 0.2
1.014
3
524.3
− 5.3
0.909
4
461.3
−11.3
.819
5
403.5
−18.2
.735
6
351.8
−25.2
.658
7
305.3
−32.3
.589
8
264.0
−39.4
.524
9
227.3
−45.5
.463
10
195.8
−50.8
.409
11
168.0
−53.4
.355
12
144.0
−54.2
.305
13
123.0
−54.3
.261
14
105.0
−54.1
.223
15
90.0
−54
.191
16
76.5
−54
.162
17
65.6
−54
.139
18
56.2
−54
.119
19
48.1
−54
.102
20
41.1
−54
.087
Table 4
Upper Air Observations: Summer Means for Continental Europe
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Vapor Pressure mm Hg
Density kg/m3
0
762.5
14.8
10.5
1.224
0.5
718.8
13.6
9.2
1.159
1.0
677.2
11.8
7.8
1.100
1.5
637.8
9.0
6.2
1.046
2.0
600.3
6.3
5.0
0.995
2.5
564.7
3.6
4.0
.946
3
530.8
+ 1.0
3.1
.898
4
468.2
− 4.3
1.9
.808
5
411.9
− 9.9
1.1
.727
6
361.3
−16.3
0.6
.653
7
315.8
−23.3
.587
8
275.0
−30.8
.527
9
238.4
−38.3
.472
10
205.8
−44.9
.419
11
176.9
−50.1
.369
12
151.8
−52.9
.319
13
130.1
−52.8
.274
14
111.6
−52.4
.234
15
95.7
−52.0
.201
16
82.0
−51.6
.172
17
70.3
−51.1
.148
18
60.3
−50.2
.127
19
51.7
−49.6
.109
20
44.4
−49.0
.093
25
20.6
.043
30
9.6
.020
35
4.5
.009
40
2.1
.004
The values below 15 km are the average of over 100 observations, while those above 15 km result from a rapidly decreasing number. The observations were made between latitudes 48–51°.
Table 5
Upper Air Observations: Winter Means for Continental Europe
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Vapor Pressure mm Hg
Density kg/m3
0
763.3
+ 1.7
4.7
1.288
0.5
717.4
+ 1.2
4.3
1.212
1.0
674.1
− 0.6
3.6
1.147
1.5
633.1
− 2.3
2.9
1.084
2.0
594.4
− 4.2
2.3
1.025
2.5
557.7
− 6.5
1.7
0.970
3
523.0
− 9.1
1.3
.920
4
458.9
−15.3
0.7
.827
5
401.3
−22.2
.743
6
349.6
−29.3
.666
7
303.3
−36.6
.596
8
261.9
−43.6
.530
9
225.4
−49.6
.469
10
193.2
−54.3
.410
11
165.2
−56.8
.355
12
141.1
−57.2
.303
13
120.5
−56.3
.259
14
103.0
−56.5
.221
15
88.0
−57.1
.189
16
75.2
−57.3
.162
17
64.2
−57.6
.138
18
54.9
−57.6
.118
19
46.9
−57.6
.101
20
40.1
−57.6
.086
25
18.3
.039
30
8.3
.018
35
3.8
.008
40
1.7
.004
The values below 12 km are the result of over 100 observations, while those above result from a rapidly decreasing number. The observations were made between latitudes 48–51°.
Table 6
Upper Air Observations: Means for Equator
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
758.9
27
1.174
1
677.3
22
1.067
2
602.3
17
0.968
3
534.8
12
.871
4
474.1
+ 6
.789
5
418.5
− 1
.714
6
368.3
− 8
.645
7
322.5
−15
.581
8
282.0
−22
.522
9
245.3
−30
.469
10
212.3
−38
.419
11
183.0
−46
.374
12
156.8
−54
.331
13
133.5
−62
.294
14
114.0
−70
.261
15
96.0
−75
.225
16
80.2
−78
.191
17
67.5
−80
.162
Table 7
Upper Air Observations—Means for Italy Altimeter Calibration Standard—Italian
1
2
3
4
5
6
Altitude km
Pressure mm Hg Altimeters
Pressure mm Hg Observations
Temperature °C
Density kg/m3
Density Relative 1.20585 to kg/m3
.0
762
761.8
15.5
1.223
1.0139
.5
717
717.2
13.2
1.160
.9622
1.0
675
675.1
10.7
1.102
.9137
1.5
635
634.7
8.0
1.046
.8678
2.0
597
596.9
5.1
.994
.8243
2.5
561
560.7
+ 2.1
.944
.7829
3.0
527
526.7
− 0.7
.897
.7435
3.5
495
494.7
− 3.6
.851
.7056
4.0
464
463.5
− 6.8
.807
.6692
4.5
435
434.8
− 9.9
.765
.6347
5.0
407
407.2
−13.3
.726
.6024
5.5
380
381.0
−16.7
.689
.5714
6.0
355
356.3
−20.2
.653
.5416
6.5
332
333.2
−23.9
.620
.5140
7.0
310
310.6
−27.7
.587
.4867
7.5
289
289.5
−31.5
.555
.4604
8.0
269
269.5
−35.2
.525
.4354
8.5
…
250.9
−38.7
.496
.4113
9.0
…
232.7
−42.0
.467
.3873
9.5
…
215.6
−45.3
.439
.3637
10.0
…
199.5
−48.3
.411
.3406
Table 8
Aircraft Performance Standard* Altimeter Calibration Standard S. T. Ae. (French) Radau Formula
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
Density Relative
0
760
15
1.225
1.000
1
715
12
1.165
0.951
2
674
9
1.110
.906
3
635
5
1.060
.865
4
597
2
1.010
.824
5
562
0
0.957
.782
6
526
− 3
.905
.739
7
493
− 6
.858
.700
8
462
− 8
.810
.662
9
434
−11
.769
.628
10
407
−13
.726
.594
11
381
−15
.686
.560
12
356
−17
.645
.526
13
333
−19
.612
.500
14
312
−20
.573
.468
15
293
−22
.542
.442
16
274
−23
.510
.416
17
257
−25
.482
.393
18
240
−27
.453
.370
19
225
−28
.427
.349
20
210
−29
.400
.327
See Table 11 for Aircraft Performance Standard now used by S. T. Ae.
Temperature. The temperature adopted for altitudes above 11.0 km is −56.5°C.
Table 12
F. A. I. Aircraft Performance Standard
1
2
3
4
5
Altitude meters
Pressure mm Hg
Constant A
Altitude meters
Density Relative
0
760
994
672.2
18756
0
1.000
2000
592.7
18522
869
0.907
3007
520.9
18286
1808
.819
4001
457.1
18116
2845
.735
5001
399.4
17895
4019
.649
5994
347.9
17681
5377
.563
6991
301.8
17452
6952
.469
7992
260.7
17217
8903
.367
8995
224.5
16994
11523
.253
10011
192.4
16761
13379
.192
11025
164.6
16557
15976
.128
12034
140.7
16382
17390
.103
13018
120.6
16260
20360
.064
14008
103.2
16145
15003
82.2
16037
15971
75.7
15973
16985
64.5
15869
Table 13a
Temperature Correction Table for Altimeter Calibration Standard United States
Mean Temp. °C
Isothermal Altitude
5000
10000
15000
20000
25000
30000
35000
40000
10
10
0
0
0
0
0
0
0
0
9
11
20
40
50
70
90
110
. . . .
. . . .
8
12
40
70
110
140
180
210
. . . .
. . . .
7
13
50
110
160
210
270
320
. . . .
. . . .
6
14
70
140
210
280
350
420
. . . .
. . . .
5
15
90
180
270
350
440
530
. . . .
. . . .
0
20
180
350
530
710
880
1060
1240
1410
− 5
25
270
530
800
1060
1330
1590
1850
2120
−10
30
350
710
1060
1410
1770
2120
2470
2830
−15
440
880
1330
1770
2210
2650
3090
3530
−20
530
1060
1590
2120
2650
3180
3710
4240
−25
620
1240
1860
2470
3090
3710
4330
4950
−30
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
4950
5660
Table 13
Altimeter Calibration Standard—United States
1
2
3
1
2
3
Altitude 1000 ft.
Pressure Millimeters of Hg
Pressure Inches of Hg
Altitude 1000 ft.
Millimeters of Hg
Inches of Hg
0
759.6
29.90
30
253.2
9.97
1
732.4
28.83
31
244.2
9.61
2
706.0
27.79
32
235.4
9.27
3
680.6
26.79
33
227.0
8.94
4
656.2
25.83
34
218.8
8.61
5
632.6
24.90
35
211.0
8.30
6
609.8
24.00
36
203.4
8.01
7
587.8
23.14
37
196.0
7.72
8
566.8
22.31
38
189.0
7.44
9
546.4
21.51
39
182.2
7.17
10
526.8
20.73
40
175.6
6.91
11
507.8
19.99
12
489.6
19.27
13
472.0
18.58
14
455.0
17.91
15
438.6
17.27
16
422.8
16.65
17
407.6
16.05
Temperature:The temperature is +10°C at all altitudes.
18
393.0
15.47
19
378.8
14.91
20
365.2
14.38
21
352.2
13.86
22
339.4
13.36
23
327.2
12.88
24
315.4
12.42
25
304.2
11.98
26
293.2
11.54
27
282.6
11.13
28
272.4
10.73
29
262.8
10.34
Note: For temperature correction table see page 771.
Table 14
Altimeter Calibration Standard—British
1
2
3
Altitude 1000 ft.
Pressure in Hg
Pressure mm Hg
0
29.90
759.5
1
28.82
732.0
2
27.78
705.6
3
26.77
680.0
4
25.81
655.6
5
24.88
631.9
6
23.98
609.1
7
23.11
587.0
8
22.27
565.7
9
21.47
545.3
10
20.69
525.5
11
19.95
506.7
12
19.23
488.4
13
18.53
470.7
14
17.86
453.6
15
17.22
437.4
16
16.61
421.9
17
16.00
406.4
18
15.42
391.7
19
14.86
377.4
20
14.33
364.0
21
13.80
350.5
22
13.31
338.1
23
12.83
325.9
24
12.36
313.9
25
11.92
302.8
26
11.49
291.9
27
11.07
281.2
28
10.67
271.0
29
10.29
261.4
30
9.93
252.2
Temperature: The temperature is +10°C at all altitudes.
Table 15
Altigraph Calibration Standard for Richard Barographs (French)
1
2
3
Altitude Km
Pressure mm Hg
Temperature °C
0
760
15
0.5
716
11
1.0
674
7
1.5
634
+ 3
2.0
595.5
− 1
2.5
559.5
− 5
3.0
525
− 9
Table 16
Aircraft Performance Standard—German
1
2
3
Altitude in km
Pressure mm Hg
Temperature °C
0
762
8.7
2
595
− 1.0
4
461
−11.6
6
354
−23.7
8
272
−37.0
9
240
−45.0
Table 17
Altimeter Calibration Standard—German
1
2
3
4
Altitude m
Pressure mm Hg
Temperature
Density kg/m3
0
762.0
10.0
1.250
500
717.2
7.5
1.188
1000
674.6
5.0
1.127
1500
634.2
2.5
1.069
2000
595.9
0
1.013
2500
559.7
− 2.5
0.960
3000
525.3
− 5.0
0.910
3500
492.7
− 7.5
0.862
4000
461.9
−10.0
0.815
4500
432.8
−12.5
0.770
5000
405.2
−15.0
0.729
5500
379.2
−17.5
0.689
6000
354.6
−20.0
0.651
6500
331.5
−22.5
0.614
7000
309.6
−25.0
0.579
7500
289.0
−27.5
0.546
8000
269.5
−30.0
0.515
Table 1
Observed Upper Air Temperatures and Pressures for Approximate Latitude 41° in the United States.11
Pressure mm Hg
Average Altitude in Feet
Winter
Summer
Year
700
2400
2400
2400
600
6380
6800
6600
500
11150
11750
11400
400
16650
17750
17200
300
23350
24850
24150
200
32600
34500
33600
150
38800
41000
40100
Altitude in 1000 Feet
Average Temperatures °C
Winter
Summer
Year
0
6.0
24.9
19.1
10
− 8.2
10.0
+ 2.1
20
−26.8
− 9.2
−17.0
30
−45.6
−28.1
−36.8
40
−52.0
−46.6
−50.8
50
−55.0
−56.3
−55.3
Table 2
Computation of Mean Temperature
n
Isothermal Altitude interval thousand feet
Mean temperature of the interval
∑tn
1
0– 1
14
14
14
2
1– 2
11
25
12.5
3
2– 3
9
34
11.5
4
3– 4
8
42
10.5
5
4– 5
6
48
9.5
6
5– 6
4
52
8.5
7
6– 7
1.5
53.5
7.5
8
7– 8
−1.5
52
6.5
9
8– 9
−4
48
5.5
10
9–10
−5
43
4.5
11
10–11
−7
36
3.5
Table 4
Gravity Correction for Altitude
Altitude, h 1000 Feet
Additive Correction Feet
0
0
5
1
10
5
15
11
20
19
25
30
30
40
35
54
40
71
Table 5
Gravity Correction for Latitude
N. or S. Latitude
Altitude in 1000 feet, h
0
5
10
15
20
0
0
+13
+27
+39
+52
10
0
+13
+25
+37
+49
20
0
+10
+21
+30
+40
30
0
+ 7
+14
+19
+26
40
0
+ 2
+ 5
+ 6
+ 8
45
0
0
0
0
0
50
0
− 2
− 4
− 7
− 9
60
0
− 6
−13
−20
−27
70
0
−10
−20
−30
−41
Tables (22)
Table 1
Upper Air Observations: Average Yearly for United States
1
2
3
4
5
6
Altitude 1000 ft.
Pressure mm Hg
Temperature °C
Vapor Pressures mm Hg
Density kg/m3
Density Relative to 1.225 kg/m3
0
760.0
19.1
10.54
1.202
0.981
1
736.4
17.1
9.27
1.172
.956
2
710.2
15.1
8.05
1.140
.930
3
685.0
13.1
7.01
1.108
.904
4
659.9
11.7
6.15
1.073
.876
5
637.0
10.4
5.41
1.040
.849
6
614.2
9.3
4.78
1.006
.821
7
592.1
7.5
4.17
0.977
.798
8
570.5
5.7
3.58
.948
.774
9
549.4
3.9
3.07
.919
.750
10
528.3
+ 2.1
2.64
.890
.727
11
507.8
+ 0.2
2.26
.862
.704
12
488.7
− 1.5
1.93
.835
.682
13
469.9
− 3.4
1.65
.808
.660
14
452.1
− 5.4
1.40
.783
.639
15
435.1
− 7.2
1.17
.758
.619
16
418.9
− 9.0
0.99
.736
.601
17
402.3
−11.0
.81
.712
.582
18
387.1
−13.0
.69
.690
.564
19
371.6
−15.0
.56
.668
.545
20
356.1
−17.0
.48
.645
.527
21
341.9
−19.0
.41
.624
.510
22
327.9
−21.1
.33
.605
.494
23
313.9
−23.2
.28
.584
.477
24
301.5
−25.2
.23
.565
.461
25
289.3
−27.2
.20
.546
.446
26
277.4
−29.2
.18
.528
.431
27
265.7
−31.2
.15
.510
.416
28
254.3
−33.1
.13
.492
.402
29
243.6
−35.0
.10
.476
.389
30
233.7
−36.8
.08
.459
.375
31
225
−38.7
.444
.362
32
216
−40.3
.428
.349
33
206
−41.9
.413
.337
34
197
−43.5
.398
.325
35
188
−45.0
.03
.383
.313
36
179
−46.7
.369
.301
37
171
−47.9
.355
.290
38
164
−49.0
.340
.278
39
158
−50.0
.327
.267
40
151
−50.8
.009
.313
.256
45
119
−54.0
.006
.251
.205
50
95
−55.3
.004
.199
.162
Table 2
Upper Air Observations: Means for Canada
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
762.8
9.0
1.258
1
677.3
5.3
1.134
2
598.5
+ 1.8
1.011
3
527.3
− 3.4
0.905
4
463.5
− 8.9
.815
5
407.3
−15.3
.733
6
356.3
−22.1
.662
7
309.8
−29.5
.592
8
268.5
−37.1
.528
9
231.8
−43.7
.470
10
199.5
−49.8
.415
11
171.0
−53.7
.365
12
146.2
−56.8
.314
13
125.2
−59.0
.268
14
106.5
−59.5
.233
15
90.0
−62.0
.198
The observations were made in latitude 43° approximately.
Table 3
Upper Air Observations Mean for S. E. England
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
760.5
9.0
1.253
1
675.1
5.0
1.128
2
596.3
+ 0.2
1.014
3
524.3
− 5.3
0.909
4
461.3
−11.3
.819
5
403.5
−18.2
.735
6
351.8
−25.2
.658
7
305.3
−32.3
.589
8
264.0
−39.4
.524
9
227.3
−45.5
.463
10
195.8
−50.8
.409
11
168.0
−53.4
.355
12
144.0
−54.2
.305
13
123.0
−54.3
.261
14
105.0
−54.1
.223
15
90.0
−54
.191
16
76.5
−54
.162
17
65.6
−54
.139
18
56.2
−54
.119
19
48.1
−54
.102
20
41.1
−54
.087
Table 4
Upper Air Observations: Summer Means for Continental Europe
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Vapor Pressure mm Hg
Density kg/m3
0
762.5
14.8
10.5
1.224
0.5
718.8
13.6
9.2
1.159
1.0
677.2
11.8
7.8
1.100
1.5
637.8
9.0
6.2
1.046
2.0
600.3
6.3
5.0
0.995
2.5
564.7
3.6
4.0
.946
3
530.8
+ 1.0
3.1
.898
4
468.2
− 4.3
1.9
.808
5
411.9
− 9.9
1.1
.727
6
361.3
−16.3
0.6
.653
7
315.8
−23.3
.587
8
275.0
−30.8
.527
9
238.4
−38.3
.472
10
205.8
−44.9
.419
11
176.9
−50.1
.369
12
151.8
−52.9
.319
13
130.1
−52.8
.274
14
111.6
−52.4
.234
15
95.7
−52.0
.201
16
82.0
−51.6
.172
17
70.3
−51.1
.148
18
60.3
−50.2
.127
19
51.7
−49.6
.109
20
44.4
−49.0
.093
25
20.6
.043
30
9.6
.020
35
4.5
.009
40
2.1
.004
The values below 15 km are the average of over 100 observations, while those above 15 km result from a rapidly decreasing number. The observations were made between latitudes 48–51°.
Table 5
Upper Air Observations: Winter Means for Continental Europe
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Vapor Pressure mm Hg
Density kg/m3
0
763.3
+ 1.7
4.7
1.288
0.5
717.4
+ 1.2
4.3
1.212
1.0
674.1
− 0.6
3.6
1.147
1.5
633.1
− 2.3
2.9
1.084
2.0
594.4
− 4.2
2.3
1.025
2.5
557.7
− 6.5
1.7
0.970
3
523.0
− 9.1
1.3
.920
4
458.9
−15.3
0.7
.827
5
401.3
−22.2
.743
6
349.6
−29.3
.666
7
303.3
−36.6
.596
8
261.9
−43.6
.530
9
225.4
−49.6
.469
10
193.2
−54.3
.410
11
165.2
−56.8
.355
12
141.1
−57.2
.303
13
120.5
−56.3
.259
14
103.0
−56.5
.221
15
88.0
−57.1
.189
16
75.2
−57.3
.162
17
64.2
−57.6
.138
18
54.9
−57.6
.118
19
46.9
−57.6
.101
20
40.1
−57.6
.086
25
18.3
.039
30
8.3
.018
35
3.8
.008
40
1.7
.004
The values below 12 km are the result of over 100 observations, while those above result from a rapidly decreasing number. The observations were made between latitudes 48–51°.
Table 6
Upper Air Observations: Means for Equator
1
2
3
4
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
0
758.9
27
1.174
1
677.3
22
1.067
2
602.3
17
0.968
3
534.8
12
.871
4
474.1
+ 6
.789
5
418.5
− 1
.714
6
368.3
− 8
.645
7
322.5
−15
.581
8
282.0
−22
.522
9
245.3
−30
.469
10
212.3
−38
.419
11
183.0
−46
.374
12
156.8
−54
.331
13
133.5
−62
.294
14
114.0
−70
.261
15
96.0
−75
.225
16
80.2
−78
.191
17
67.5
−80
.162
Table 7
Upper Air Observations—Means for Italy Altimeter Calibration Standard—Italian
1
2
3
4
5
6
Altitude km
Pressure mm Hg Altimeters
Pressure mm Hg Observations
Temperature °C
Density kg/m3
Density Relative 1.20585 to kg/m3
.0
762
761.8
15.5
1.223
1.0139
.5
717
717.2
13.2
1.160
.9622
1.0
675
675.1
10.7
1.102
.9137
1.5
635
634.7
8.0
1.046
.8678
2.0
597
596.9
5.1
.994
.8243
2.5
561
560.7
+ 2.1
.944
.7829
3.0
527
526.7
− 0.7
.897
.7435
3.5
495
494.7
− 3.6
.851
.7056
4.0
464
463.5
− 6.8
.807
.6692
4.5
435
434.8
− 9.9
.765
.6347
5.0
407
407.2
−13.3
.726
.6024
5.5
380
381.0
−16.7
.689
.5714
6.0
355
356.3
−20.2
.653
.5416
6.5
332
333.2
−23.9
.620
.5140
7.0
310
310.6
−27.7
.587
.4867
7.5
289
289.5
−31.5
.555
.4604
8.0
269
269.5
−35.2
.525
.4354
8.5
…
250.9
−38.7
.496
.4113
9.0
…
232.7
−42.0
.467
.3873
9.5
…
215.6
−45.3
.439
.3637
10.0
…
199.5
−48.3
.411
.3406
Table 8
Aircraft Performance Standard* Altimeter Calibration Standard S. T. Ae. (French) Radau Formula
1
2
3
4
5
Altitude km
Pressure mm Hg
Temperature °C
Density kg/m3
Density Relative
0
760
15
1.225
1.000
1
715
12
1.165
0.951
2
674
9
1.110
.906
3
635
5
1.060
.865
4
597
2
1.010
.824
5
562
0
0.957
.782
6
526
− 3
.905
.739
7
493
− 6
.858
.700
8
462
− 8
.810
.662
9
434
−11
.769
.628
10
407
−13
.726
.594
11
381
−15
.686
.560
12
356
−17
.645
.526
13
333
−19
.612
.500
14
312
−20
.573
.468
15
293
−22
.542
.442
16
274
−23
.510
.416
17
257
−25
.482
.393
18
240
−27
.453
.370
19
225
−28
.427
.349
20
210
−29
.400
.327
See Table 11 for Aircraft Performance Standard now used by S. T. Ae.