the safety of passengers was uppermost in our minds

• Perhaps the closest analogy is comet Lovejoy, which in 2011 passed through the uppermost reaches of the solar atmosphere and emerged mostly intact.
  Scientific American Nov 30, 2013
• The mission's primary objective is to separate Earth's geomagnetic field from the magnetic field induced in the uppermostmagnetosphere by the Sun's charged particles.
  Scientific American Nov 22, 2013
• For now it is the threats that appear uppermost in the thinking of the Islamic Republic, as it surveys its diminished economy and regional upheaval.
  Reuters Sep 30, 2013
• For the roll of a dice, whereby the cube must end up with one of six faces uppermost, equals six.
  Nature Sep 12, 2013