A flame detection apparatus comprising: a first optical sensor comprising a first long wave pass filter, having a first spectral response; a second optical sensor comprising a second long wave pass filter having a second spectral response; and a third optical sensor comprising a third long wave pass filter having a third spectral response; and wherein said third spectral response is a subset of said second response, and said second response is a subset of said first spectral response, wherein said first, second and third spectral responses are specified at respective first, second and third minimum wavelengths above which each said filter responds at least at fifty percent transmittance, and wherein said first minimum wavelength is between about 2.3 pm and about 2.8 pm, said second minimum wavelength is between about 3.2 pm and about 3.8 pm, and said third minimum wavelength is within about 1% of 4.17 pm, further comprising a computer-based processor for analyzing a first, second, and third signal received from said first, second and third sensor, and issuing a command signal, and an output responsive to said command signal, wherein said computer-based processor includes a computer-readable medium configured with control logic to command said processor to execute a detection method, said method comprising the steps of: comparing a first ratio to a first threshold, said first ratio being a ratio of said second signal to said first signal; and comparing a second ratio to a second threshold, said second ratio being a ratio of said third signal to said second signal. a first optical sensor comprising a first long wave pass filter, having a first spectral response; a second optical sensor comprising a second long wave pass filter having a second spectral response; and a third optical sensor comprising a third long wave pass filter having a third spectral response; and wherein said third spectral response is a subset of said second response, and said second response is a subset of said first spectral response, wherein said first, second and third spectral responses are specified at respective first, second and third minimum wavelengths above which each said filter responds at least at fifty percent transmittance, and wherein said first minimum wavelength is between about 2.3 pm and about 2.8 pm, said second minimum wavelength is between about 3.2 pm and about 3.8 pm, and said third minimum wavelength is within about 1% of 4.17 pm, further comprising a computer-based processor for analyzing a first, second, and third signal received from said first, second and third sensor, and issuing a command signal, and an output responsive to said command signal, wherein said computer-based processor includes a computer-readable medium configured with control logic to command said processor to execute a detection method, said method comprising the steps of: comparing a first ratio to a first threshold, said first ratio being a ratio of said second signal to said first signal; and comparing a second ratio to a second threshold, said second ratio being a ratio of said third signal to said second signal. comparing a first ratio to a first threshold, said first ratio being a ratio of said second signal to said first signal; and comparing a second ratio to a second threshold, said second ratio being a ratio of said third signal to said second signal. <EOS>