Effects as a function of altitude. The human body can perform best at sea level, where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition). The concentration of oxygen (O2) in sea-level air is 20.9%, so the partial pressure of O2 (pO2) is 21.136 kPa.
On Tuesday, the New York-based carrier rolled out a new three-tier structure for fares, giving the cheapest fares to passengers without checked bags. The airline's new fare types are labeled Blue, Blue Plus and Blue Flex, according to notices posted on JetBlue.com. Price differences between the tiers will vary, but Blue fares generally will be $15 cheaper than Blue Plus, and Blue Flex will be about $85 higher than that, according to JetBlue.
JetBlue will cut leg room, charge for checked bags. JetBlue's Blue Fare fees range from $20 to $25 for a first checked bag, while the Blue Plus includes two bags. All passengers will pay $100 for a third checked bag. For a domestic flight, many major U.S. airlines charge $25 for a passenger's first checked bag and $35 for the second bag. A handful say on their websites that they charge $150 for the third checked bag and $200 for any additional pieces.