  We present observations towards one of the closest regions of high mass star
formation, Orion BN/KL, performed at both low resolution mode (grating mode)
and high resolution mode (Fabry-Perot) with the Long Wavelength Spectrometer on
board the Infrared Space Observatory. We detected the CO rotational lines from
Jup = 15 to Jup = 45. While the lines with Jup<= 32 are spectrally unresolved,
the higher lying lines show a broadened profile. Finally, we detected two 13CO
lines, namely at Jup = 18 and 24, from which we could derive the opacities of
the relative 12CO lines. The LVG analysis of the observed line spectrum allows
to distinguish three main physical components with different temperatures,
densities and column densities: 1) lines with Jup< 20 originate mainly in the
diffuse photodissociation region surrounding the source; 2) lines with Jup
between 20 and 30 originate in the high velocity outflow (plateau) emanating
from IrC2; 3) lines with Jup > 32 originate in the hot and dense gas of the
shocked component of the outflow. We discuss how future observations with HIFI,
onboard the Far Infrared Space Telescope (FIRST) will allow to spectrally and
spatially disentangle the three components, and, consequently, characterise
more precisely the Orion BN/KL star forming region.
