| Building Altimeters
The AT2510-16A is commonly used
in digital altimeters. The pressure vs. altitude for a "standard
atmosphere" is shown below. The standard atmosphere is based
on measurements of the pressure vs. altitude at various locations
on the earth. Altimeters used in aircraft are based on the standard
atmosphere.
How close is the standard atmosphere
to the actual atmosphere?
A barometric altimeter will have a scale
error of approximately -0.2% for each degree F hotter than standard
the actual atmosphere is. When the atmosphere is hotter than standard,
a barometric altimeter will underreport the actual altitude change.
Standard Atmospheric Pressure
vs. Altitude
Reference U.S. Standard Atmosphere,
1962. NASA. US Air Force, and U.S. Weather Bur.,Dec. 1962.
Exact fit functions to the tabulated pressure vs. altitude
data were determined.
Three functions are used to cover the 0 to 100,000 ft range.
Over the altitude range 0 to 36,000 feet.
2 3 4 5
( c0 + c1 x Alt + c2 x Alt + c3 x Alt + c4 x Alt + c5 x Alt )
P = P0 e
Over
the altitude range 36,000 to 65,600 feet.
( c0 + c1 x Alt )
P = P0 e
Over
the altitude range 65,600 to 100,000 feet.
2 3
( c0 + c1 x Alt + c2 x Alt + c3 x Alt )
P = P0 e
|
Pressure vs. Altitude
|
|
Altitude in 200 foot increments. Pressure
in In-Hg.
|
|
|
000
|
200
|
400
|
600
|
800
|
|
0
|
29.9213
|
29.7056
|
29.4913
|
29.2782
|
29.0663
|
|
1,000
|
28.8557
|
28.6463
|
28.4382
|
28.2312
|
28.0255
|
|
2,000
|
27.8211
|
27.6178
|
27.4157
|
27.2148
|
27.0152
|
|
3,000
|
26.8167
|
26.6194
|
26.4232
|
26.2283
|
26.0345
|
|
4,000
|
25.8418
|
25.6504
|
25.4600
|
25.2709
|
25.0828
|
|
5,000
|
24.8959
|
24.7101
|
24.5255
|
24.3420
|
24.1595
|
|
6,000
|
23.9782
|
23.7980
|
23.6189
|
23.4409
|
23.2640
|
|
7,000
|
23.0881
|
22.9134
|
22.7397
|
22.5670
|
22.3955
|
|
8,000
|
22.2250
|
22.0555
|
21.8871
|
21.7197
|
21.5534
|
|
9,000
|
21.3881
|
21.2239
|
21.0606
|
20.8984
|
20.7372
|
|
10,000
|
20.5770
|
20.4178
|
20.2596
|
20.1024
|
19.9462
|
|
11,000
|
19.7909
|
19.6367
|
19.4834
|
19.3311
|
19.1797
|
|
12,000
|
19.0294
|
18.8799
|
18.7315
|
18.5839
|
18.4374
|
|
13,000
|
18.2917
|
18.1470
|
18.0032
|
17.8603
|
17.7184
|
|
14,000
|
17.5774
|
17.4373
|
17.2981
|
17.1597
|
17.0223
|
|
15,000
|
16.8858
|
16.7502
|
16.6154
|
16.4816
|
16.3486
|
|
16,000
|
16.2164
|
16.0852
|
15.9548
|
15.8252
|
15.6966
|
|
17,000
|
15.5687
|
15.4417
|
15.3156
|
15.1903
|
15.0658
|
|
18,000
|
14.9421
|
14.8193
|
14.6973
|
14.5761
|
14.4557
|
|
19,000
|
14.3361
|
14.2173
|
14.0993
|
13.9821
|
13.8657
|
|
20,000
|
13.7501
|
13.6353
|
13.5212
|
13.4079
|
13.2954
|
|
21,000
|
13.1837
|
13.0727
|
12.9625
|
12.8530
|
12.7443
|
|
22,000
|
12.6363
|
12.5291
|
12.4226
|
12.3168
|
12.2118
|
|
23,000
|
12.1075
|
12.0039
|
11.9010
|
11.7989
|
11.6974
|
|
24,000
|
11.5967
|
11.4967
|
11.3974
|
11.2987
|
11.2008
|
|
25,000
|
11.1035
|
11.0070
|
10.9111
|
10.8159
|
10.7213
|
|
26,000
|
10.6275
|
10.5343
|
10.4418
|
10.3499
|
10.2587
|
|
27,000
|
10.1681
|
10.0782
|
9.9889
|
9.9003
|
9.8123
|
|
28,000
|
9.7249
|
9.6382
|
9.5521
|
9.4666
|
9.3817
|
|
29,000
|
9.2975
|
9.2139
|
9.1309
|
9.0485
|
8.9666
|
|
30,000
|
8.8854
|
8.8048
|
8.7248
|
8.6454
|
8.5665
|
|
31,000
|
8.4883
|
8.4106
|
8.3335
|
8.2570
|
8.1810
|
|
32,000
|
8.1056
|
8.0308
|
7.9565
|
7.8828
|
7.8097
|
|
33,000
|
7.7371
|
7.6650
|
7.5935
|
7.5225
|
7.4521
|
|
34,000
|
7.3822
|
7.3128
|
7.2440
|
7.1757
|
7.1079
|
|
35,000
|
7.0406
|
6.9739
|
6.9076
|
6.8419
|
6.7767
|
|
36,000
|
6.7120
|
6.6477
|
6.5842
|
6.5212
|
6.4588
|
|
37,000
|
6.3970
|
6.3358
|
6.2752
|
6.2151
|
6.1557
|
|
38,000
|
6.0968
|
6.0385
|
5.9807
|
5.9235
|
5.8668
|
|
39,000
|
5.8107
|
5.7551
|
5.7001
|
5.6455
|
5.5915
|
|
40,000
|
5.5380
|
5.4850
|
5.4326
|
5.3806
|
5.3291
|
|
41,000
|
5.2781
|
5.2276
|
5.1776
|
5.1281
|
5.0790
|
|
42,000
|
5.0305
|
4.9823
|
4.9347
|
4.8875
|
4.8407
|
|
43,000
|
4.7944
|
4.7485
|
4.7031
|
4.6581
|
4.6135
|
|
44,000
|
4.5694
|
4.5257
|
4.4824
|
4.4395
|
4.3970
|
|
45,000
|
4.3550
|
4.3133
|
4.2721
|
4.2312
|
4.1907
|
|
46,000
|
4.1506
|
4.1109
|
4.0716
|
4.0326
|
3.9940
|
|
47,000
|
3.9558
|
3.9180
|
3.8805
|
3.8434
|
3.8066
|
|
48,000
|
3.7702
|
3.7341
|
3.6984
|
3.6630
|
3.6280
|
|
49,000
|
3.5933
|
3.5589
|
3.5249
|
3.4911
|
3.4577
|
|
50,000
|
3.4247
|
3.3919
|
3.3594
|
3.3273
|
3.2955
|
|
51,000
|
3.2640
|
3.2327
|
3.2018
|
3.1712
|
3.1408
|
|
52,000
|
3.1108
|
3.0810
|
3.0516
|
3.0224
|
2.9934
|
|
53,000
|
2.9648
|
2.9364
|
2.9084
|
2.8805
|
2.8530
|
|
54,000
|
2.8257
|
2.7986
|
2.7719
|
2.7454
|
2.7191
|
|
55,000
|
2.6931
|
2.6673
|
2.6418
|
2.6165
|
2.5915
|
|
56,000
|
2.5667
|
2.5421
|
2.5178
|
2.4937
|
2.4699
|
|
57,000
|
2.4463
|
2.4229
|
2.3997
|
2.3767
|
2.3540
|
|
58,000
|
2.3315
|
2.3092
|
2.2871
|
2.2652
|
2.2435
|
|
59,000
|
2.2221
|
2.2008
|
2.1797
|
2.1589
|
2.1382
|
|
60,000
|
2.1178
|
2.0975
|
2.0775
|
2.0576
|
2.0379
|
|
61,000
|
2.0184
|
1.9991
|
1.9800
|
1.9610
|
1.9423
|
|
62,000
|
1.9237
|
1.9053
|
1.8871
|
1.8690
|
1.8511
|
|
63,000
|
1.8334
|
1.8159
|
1.7985
|
1.7813
|
1.7643
|
|
64,000
|
1.7474
|
1.7307
|
1.7141
|
1.6977
|
1.6815
|
|
65,000
|
1.6654
|
1.6494
|
1.6337
|
1.6180
|
1.6026
|
|
66,000
|
1.5872
|
1.5721
|
1.5570
|
1.5422
|
1.5274
|
|
67,000
|
1.5128
|
1.4984
|
1.4841
|
1.4699
|
1.4559
|
|
68,000
|
1.4420
|
1.4283
|
1.4147
|
1.4012
|
1.3878
|
|
69,000
|
1.3746
|
1.3615
|
1.3486
|
1.3357
|
1.3230
|
|
70,000
|
1.3105
|
1.2980
|
1.2857
|
1.2735
|
1.2614
|
|
71,000
|
1.2494
|
1.2375
|
1.2258
|
1.2141
|
1.2026
|
|
72,000
|
1.1912
|
1.1799
|
1.1687
|
1.1577
|
1.1467
|
|
73,000
|
1.1358
|
1.1251
|
1.1144
|
1.1039
|
1.0935
|
|
74,000
|
1.0831
|
1.0729
|
1.0627
|
1.0527
|
1.0427
|
|
75,000
|
1.0329
|
1.0231
|
1.0135
|
1.0039
|
0.9945
|
|
76,000
|
0.9851
|
0.9758
|
0.9666
|
0.9575
|
0.9485
|
|
77,000
|
0.9395
|
0.9307
|
0.9219
|
0.9132
|
0.9047
|
|
78,000
|
0.8961
|
0.8877
|
0.8794
|
0.8711
|
0.8629
|
|
79,000
|
0.8548
|
0.8468
|
0.8389
|
0.8310
|
0.8232
|
|
80,000
|
0.8155
|
0.8078
|
0.8002
|
0.7927
|
0.7853
|
|
81,000
|
0.7780
|
0.7707
|
0.7635
|
0.7563
|
0.7492
|
|
82,000
|
0.7422
|
0.7353
|
0.7284
|
0.7216
|
0.7149
|
|
83,000
|
0.7082
|
0.7016
|
0.6950
|
0.6885
|
0.6821
|
|
84,000
|
0.6758
|
0.6695
|
0.6632
|
0.6570
|
0.6509
|
|
85,000
|
0.6448
|
0.6388
|
0.6329
|
0.6270
|
0.6212
|
|
86,000
|
0.6154
|
0.6097
|
0.6040
|
0.5984
|
0.5928
|
|
87,000
|
0.5873
|
0.5819
|
0.5765
|
0.5711
|
0.5658
|
|
88,000
|
0.5606
|
0.5554
|
0.5502
|
0.5451
|
0.5401
|
|
89,000
|
0.5351
|
0.5301
|
0.5252
|
0.5203
|
0.5155
|
|
90,000
|
0.5107
|
0.5060
|
0.5013
|
0.4967
|
0.4921
|
|
91,000
|
0.4876
|
0.4831
|
0.4786
|
0.4742
|
0.4698
|
|
92,000
|
0.4655
|
0.4612
|
0.4569
|
0.4527
|
0.4485
|
|
93,000
|
0.4444
|
0.4403
|
0.4363
|
0.4322
|
0.4283
|
|
94,000
|
0.4243
|
0.4204
|
0.4166
|
0.4127
|
0.4089
|
|
95,000
|
0.4052
|
0.4014
|
0.3978
|
0.3941
|
0.3905
|
|
96,000
|
0.3869
|
0.3834
|
0.3798
|
0.3764
|
0.3729
|
|
97,000
|
0.3695
|
0.3661
|
0.3628
|
0.3594
|
0.3561
|
|
98,000
|
0.3529
|
0.3496
|
0.3465
|
0.3433
|
0.3401
|
|
99,000
|
0.3370
|
0.3340
|
0.3309
|
0.3279
|
0.3249
|
<
Back to Articles |
