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Altimeter 3066
A very high pressure settled in Pacific NW: KPSC 020453Z 31006KT 6SM BR BKN007 BKN075 M07/M08 A3066 RMK AO2 SLP389 T10671078 That's the highest that I've ever remember seeing. I always thought that the NW seems to have larger pressure swings (probably more so in Alaska). We can go from 2960 to 3060 in about two days. |
#2
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Altimeter 3066
BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). M wrote: A very high pressure settled in Pacific NW: KPSC 020453Z 31006KT 6SM BR BKN007 BKN075 M07/M08 A3066 RMK AO2 SLP389 T10671078 That's the highest that I've ever remember seeing. I always thought that the NW seems to have larger pressure swings (probably more so in Alaska). We can go from 2960 to 3060 in about two days. |
#3
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Altimeter 3066
"M" wrote in message ps.com... BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). The Kollsman Window is only required to have a range of 28.00 to 31.00 inches Hg. So if barometric pressure is outside that range, you cannot accurately set most altimeters. John Severyn @KLVK |
#4
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Altimeter 3066
I don't believe VFR flight requires accurate altimeter adjustable for barometric pressure. 91.205 only requires such altimeter for IFR operations. J. Severyn wrote: "M" wrote in message ps.com... BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). The Kollsman Window is only required to have a range of 28.00 to 31.00 inches Hg. So if barometric pressure is outside that range, you cannot accurately set most altimeters. John Severyn @KLVK |
#5
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Altimeter 3066
I don't believe VFR flight requires accurate altimeter adjustable for
barometric pressure. 91.205 only requires such altimeter for IFR operations. J. Severyn wrote: "M" wrote in message ps.com... BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). The Kollsman Window is only required to have a range of 28.00 to 31.00 inches Hg. So if barometric pressure is outside that range, you cannot accurately set most altimeters. John Severyn @KLVK |
#6
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Altimeter 3066
Correct. But you still are required to follow the NOTAM in extremely high
or low barometric pressure conditions. If you read FAR91.144 quoted he "Sec. 91.144 Temporary restriction on flight operations during abnormally high barometric pressure conditions. (a) Special flight restrictions. When any information indicates that barometric pressure on the route of flight currently exceeds or will exceed 31 inches of mercury, no person may operate an aircraft or initiate a flight contrary to the requirements established by the Administrator and published in a Notice to Airmen issued under this section. (b) Waivers. The Administrator is authorized to waive any restriction issued under paragraph (a) of this section to permit emergency supply, transport, or medical services to be delivered to isolated communities, where the operation can be conducted with an acceptable level of safety." In other words, it says "Read the NOTAM" or "Get a Waiver". Normally the NOTAM will restrict operation at certain altitudes so that safe altitude separation can be maintained in spite of the inability to correctly enter the barometric pressure. John Severyn @KLVK "M" wrote in message oups.com... I don't believe VFR flight requires accurate altimeter adjustable for barometric pressure. 91.205 only requires such altimeter for IFR operations. J. Severyn wrote: "M" wrote in message ps.com... BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). The Kollsman Window is only required to have a range of 28.00 to 31.00 inches Hg. So if barometric pressure is outside that range, you cannot accurately set most altimeters. John Severyn @KLVK |
#7
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Altimeter 3066
"M" wrote in message oups.com... I don't believe VFR flight requires accurate altimeter adjustable for barometric pressure. 91.205 only requires such altimeter for IFR operations. AIM 7-2-2 might answer your question about high and low barometric pressures. John Severyn @KLVK |
#8
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Altimeter 3066
That is the highest pressure you can set on the Kollsman
window. "M" wrote in message ps.com... | | BTW, FAR 91.144 restricts flight operations when barometric pressure | exceeds 31 inch mercury. Any idea why? (note this restriction applies | to VFR traffic a well). | | | M wrote: | A very high pressure settled in Pacific NW: | | KPSC 020453Z 31006KT 6SM BR BKN007 BKN075 M07/M08 A3066 RMK AO2 | SLP389 T10671078 | | That's the highest that I've ever remember seeing. | | I always thought that the NW seems to have larger pressure swings | (probably more so in Alaska). We can go from 2960 to 3060 in about two | days. | |
#9
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Altimeter 3066
Heck,,, get out and go flying. The wings love the thick air and the
motor really LOVES it too. M wrote: A very high pressure settled in Pacific NW: KPSC 020453Z 31006KT 6SM BR BKN007 BKN075 M07/M08 A3066 RMK AO2 SLP389 T10671078 That's the highest that I've ever remember seeing. I always thought that the NW seems to have larger pressure swings (probably more so in Alaska). We can go from 2960 to 3060 in about two days. |
#10
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Altimeter 3066
M wrote:
BTW, FAR 91.144 restricts flight operations when barometric pressure exceeds 31 inch mercury. Any idea why? (note this restriction applies to VFR traffic a well). The "why" is that the altimeter setting range on most altimeters doesn't go past 31.00". Does anyone have an example of a NOTAM under 91.144? (how restrictive is it). The rules that apply in Canada are a bit more explicit: http://www.tc.gc.ca/CivilAviation/pu...12-1.htm#12-12 Basically it says - for enroute, set the altimeter to 31" - for IFR approaches, set the altimeter to the actual altimeter setting if able, otherwise set it to 31" and adjust the altitude minima (add 100' and 1/4 SM per 0.1" above 31.00") - aerodromes which cannot report the actual altimeter setting are restricted to VFR. -"For aircraft operating VFR, no additional restrictions apply; however, extra diligence in flight planning and in operating in these conditions is essential. " |
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