LGT CAPT ALMOST ENTERED P56 AIRSPACE ON RIVER VISUAL APCH TO DCA.

Narrative

ON VISUAL RIVER APCH TO RWY 18 AT DCA; I MADE A BAD APCH; ALMOST GOING INTO P56; WITH AN AIR SAFETY INSPECTOR ON JUMP SEAT. LOOKING BACK; THINGS WERE NORMAL UNTIL WE WERE CLRED FOR THE APCH. WE WERE HIGH AND I BECAME FIXATED ON GETTING DOWN. I NOTICED I WAS N OF COURSE AND CORRECTED BACK TO THE RIVER JUST IN TIME TO MISS P56. THE ASI SAID HE WAS ABOUT TO SAY SOMETHING TO ME WHEN I CAUGHT IT. PRIOR TO THE APCH; WE WERE SET UP FOR RNAV ON FO SIDE AND VOR ON CAPT SIDE -- I DIDN'T USE THEM. I NOW THINK THAT THERE WERE MANY FACTORS WORKING AGAINST ME TODAY; NONE VERY IMPORTANT BY ITSELF BUT ADDED TOGETHER MEANT A LOT. 1) LATE ARR THE NIGHT BEFORE AT EARLY MORNING AND 2 HR WAIT FOR HOTEL VAN AND AWAKE AT EARLY MORNING. 2) SNIFFLES ALL DAY SUNDAY. 3) MONDAY EYES ITCH; SINUS ACHE (MUST BE SOMETHING IN THE AIR). 4) LATE TRIP MONDAY. 5) TUESDAY MORNING; FULL BLOWN HEAD COLD. I HAD BEEN GETTING SICK AND DIDN'T REALIZE IT. BEFORE TKOF WITH ASI IN JUMP SEAT; I TOLD MYSELF IF I FELT SLEEPY TO GIVE ACFT TO FO. BUT I NEVER FELT SLEEPY; HOWEVER; IT SEEMS MY JUDGEMENT WENT OUT THE WINDOW. ALTHOUGH FATIGUE IS INSIDIOUS; I THINK I WILL BE QUICKER TO GIVE OVER CTL OR TAKE CTL FROM THE FO IN THE FUTURE AND BE ESPECIALLY ALERT FOR SIGNS OF COLDS AND FLU DURING THE COLD AND FLU SEASON.