The possible penetration of magnetospheric convective electric field to low latitudes is investigated with the help of VHF radar measurements of equatorial electrojet electric fields during the 1054 UT substorm of March 22, 1979. The observed time relationship of these electric fields with the southward component of the interplanetary magnetic field and the polar-auroral magnetic activity suggests that the magnetospheric convective electric fields may penetrate to low latitudes, at least on certain occasions during the growth phase of a substorm before screening by ring current becomes effective. ¿ American Geophysical Union 1987