WASHINGTON (Reuter) - An Air Force B-1 bomber crashed in Montana
 Friday, killing all four crew members aboard and bringing to six the
 number of U.S. military air crashes in a week.
     The B-1B was on a training mission out of Ellsworth Air Force
 Base in South Dakota and went down between 4:10 p.m. and 5:10 p.m.
 EDT near Alzada, Montana, a Pentagon spokesman said. It carried no
 weapons.
     "All four crew members were killed and their bodies have been
 recovered,"he said.
     An official at nearby Carter County Sheriff's Department said
 the terrain where the plane crashed was fairly flat and open.
     The official, who declined to give his name, reported that the
 weather in southeast Montana was clear and sunny Friday, and the
 temperature was in the 50s Farenheit.
     An Air Force team was on the scene and had begun an investiga-
 tion, the Pentagon spokesman said.
     President Clinton expressed his deep condolences to the families
 of the airmen killed and said he continued to have  "the highest
 confidence" in the Air Force and all U.S. military services.
    "The secretary of defense has assured the president that the
 Department of Defense will take all appropriate actions to investi-
 gate the cause of the accident and ensure the safety of all our
 military air crews," White House spokesman Joe Lockhart told repor-
 ters traveling with Clinton in California, where he escorted
 daughter Chelsea to begin her first year at Stanford University.
     The crash came just hours after the Air Force announced it would
 halt all training flights for 24 hours Sept. 26 on orders from
 Defense Secretary William Cohen for service branches to study safety
 after the recent rash of accidents.
     But the B-1 accident prompted Gen. Richard Hawley, the head of
 the Air Force's Air Combat Command, to move up suspension of opera-
 tions by four days.
     "On Monday, we will stop flying training and exercise missions
 and focus intently on what we do and how we do it," he said in a
 statement. "We need to determine why these incidents happen and how
 to prevent any more mishaps."
     Cohen this week ordered each military service to "stand-down"
 training flights for 24 hours at some time during a week-long period
 beginning Friday.
     The Navy and Marine Corps have said they will leave it up to
 individual flight units on when to hold their own 24-hour training
 halts.
     The previous five accidents included the apparent collision of
 an Air Force C-141 cargo jet and a German plane off the coast of
 Africa, the mid-air break up of an F-117A stealth fighter at an air
 show near Baltimore and the collision of two Air Force F-16s off the
 New Jersey coast. A Marine Corps F/A-18 also crashed in North Caro-
 lina and a Navy F/A-18 went down in Oman.
     Ironically, the high profile crashes coincided with celebrations
 of the Air Force's 50th birthday Thursday, a milestone that was
 marked with a morale-boosting visit from Clinton and jet fly-overs.
     But the festivities were dampened by the series of five -- now
 six -- random military aircraft accidents since last Saturday which
 have resulted in the deaths of 16 Americans.
     Cohen and military officials have stressed that the overall fly-
 ing safety record of the U.S. military this year is very similar to
 that of last year, which was the best on record.
    The swing-wing B-1 "Lancer," designed originally to carry nuclear
 bombs to the heart of Soviet territory in a world war, was first
 delivered to the Air Force by Rockwell International Corp. in 1985.
    The last plane was delivered in 1988 and the fleet is in the pro-
 cess of being modified to carry a wide range of smart conventional
 weapons, including cruise missiles.
    The big plane, 146 feet long with a wingspan of 137 feet, flies
 at a speed of 900 miles an hour and costs more than $200 million.
 23:41 09-19-97
 ADDED Items----------------------------------------------------
     "It was just a big, black mushroom cloud. It looked so black
 against the clear sky," resident Kaye Nelson said from the Valley
 Inn Bar & Cafe in Alzada.
     Ranch worker James Albertson said he, too, saw smoke in an area
 familiar to residents as an Air Force training range.  "I suspected
 the black smoke was either one of those planes hitting the dirt or
 someone burning tires," he said.
                      No Common Problem Found
     Pentagon officials maintain that no evidence exists of a common
 safety or mechanical problem linking the recent crashes.
     At the White House, President Clinton said Wednesday he had urged
 Cohen to analyze the crashes "to see if there is some pattern that
 would require some sort of review by the Air Force."
     But the president left open the possibility that crashes were
 coincidental. "I wouldn't over-jump to conclusions about this," he
 told reporters in the Oval Office. "If there is a pattern here that
 has to be looked into on air safety, you can be sure that the Air
 Force will look into it," Clinton said
     "It is easy for the American people to forget the risks that our
 men and women in uniform take," said Clinton. "Every year, we lose a
 couple of hundred people serving the United States in the military
 in peacetime. It is dangerous work."
                  Pilots Suffering From Overwork?
     Some observers, however, claim that pilots have been suffering
 fatigue. With defense spending consistently shrinking for 11 years,
 pilots in the armed services have been expected to do more with less.
     "There is a problem of people being overburdened and overtaxed
 with missions.  They're exhausted," says journalist Stacey Evers, an
 air force expert with Jane's Defence Weekly.  "First they go on a
 narcotics mission, then off to Bosnia and then to Korea. They don't
 go home for months."
     The situation has become so tight that the Air Force canceled
 many air competitions and exercises, she said.
     Many experienced pilots are also being lured away from the ser-
 vices by commercial airlines that offer far more attractive benefits
 and salaries. Many leave after completing their 10-year commitment
 and they have seasoned their skills.
     "It robs us of experienced people," said Air Force Gen. Hawley
 of Air Combat Command. Speaking this summer about the loss of pilots,
 the four-star general said: "We need to keep those experienced
 people around because they're the leaders."
--- DB 1.39/004487
-=> Quoting Jay Hanig to Don Burke <=-
JH> The math necessary is fairly simple now.  We breath air at sealevel
with a partial pressure of oxygen of 3 psi.  Take the atmospheric
pressure of any altitude and multiply it by .2 to get the partial
pressure of O2 at altitude. That is based on air, which is 20% oxygen.
JH> In the case of the 50/50 mix of nitrox, multiply atmospheric pressure
(for whatever altitude interests you) by .5 to get the partial
pressure.   Any figure that you derive that has a value of less than 2
isn't doing so well. 2 psi is the equivalent of breathing air at 10,000
feet. 
When I was riding submarines, I went a couple of days at about 2.7 psi.
It was difficult to do anything complex under those conditions.
For a shorter period, it would be okay I suppose.
The limit on the other end is oxygen toxicity which occurs somewhere 
between 15 psi and 30 psi, depending on the individual.  
People have actually died from too much oxygen.
If there is no compelling medical reason to go above about 3.5 psi 
for an individual, the extra oxygen just boosts the fire hazard.
... Turning final runway "X"......
--- Blue Wave/386 v2.20
---------------