Neutron monitor latitude surveys at aircraft altitudes

The Space Research Unit operates four stationary neutron monitors and it has conducted several latitude surveys with mobile neutron monitors. Our sea-level surveys have resulted in a clear identification of drift effects in the modulation. We have also conducted several latitude surveys at aircraft altitudes, the data of which have primarily been used to study the barometric attenuation coefficient of a neutron monitor, as well as cutoff rigidities in the Cape Town Magnetic Anomaly. In this contribution we present differential response functions of these aircraft surveys, and conclude that the drift effect is not detectable in them.